refactor(cnn): isolate CNN v2 to cnn_v2/ subdirectory

Move all CNN v2 files to dedicated cnn_v2/ directory to prepare for CNN v3 development. Zero functional changes.

Structure:
- cnn_v2/src/ - C++ effect implementation
- cnn_v2/shaders/ - WGSL shaders (6 files)
- cnn_v2/weights/ - Binary weights (3 files)
- cnn_v2/training/ - Python training scripts (4 files)
- cnn_v2/scripts/ - Shell scripts (train_cnn_v2_full.sh)
- cnn_v2/tools/ - Validation tools (HTML)
- cnn_v2/docs/ - Documentation (4 markdown files)

Changes:
- Update CMake source list to cnn_v2/src/cnn_v2_effect.cc
- Update assets.txt with relative paths to cnn_v2/
- Update includes to ../../cnn_v2/src/cnn_v2_effect.h
- Add PROJECT_ROOT resolution to Python/shell scripts
- Update doc references in HOWTO.md, TODO.md
- Add cnn_v2/README.md

Verification: 34/34 tests passing, demo runs correctly.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 0 insertions, 424 deletions

diff --git a/scripts/train_cnn_v2_full.sh b/scripts/train_cnn_v2_full.sh
deleted file mode 100755
index 078ea28..0000000
--- a/scripts/train_cnn_v2_full.sh
+++ /dev/null
@@ -1,424 +0,0 @@
-#!/bin/bash
-# Complete CNN v2 Training Pipeline
-# Train → Export → Build → Validate
-# Usage: ./train_cnn_v2_full.sh [OPTIONS]
-#
-# MODES:
-#   (none)                    Run complete pipeline: train → export → build → validate
-#   --validate                Validate only (skip training, use existing weights)
-#   --validate CHECKPOINT     Validate with specific checkpoint file
-#   --export-only CHECKPOINT  Export weights only (skip training, build, validation)
-#
-# TRAINING PARAMETERS:
-#   --epochs N                Training epochs (default: 200)
-#   --batch-size N            Batch size (default: 16)
-#   --lr FLOAT                Learning rate (default: 1e-3)
-#   --checkpoint-every N      Checkpoint interval (default: 50)
-#   --kernel-sizes K          Comma-separated kernel sizes (default: 3,3,3)
-#   --num-layers N            Number of layers (default: 3)
-#   --mip-level N             Mip level for p0-p3 features: 0-3 (default: 0)
-#   --grayscale-loss          Compute loss on grayscale instead of RGBA
-#
-# PATCH PARAMETERS:
-#   --patch-size N            Patch size (default: 8)
-#   --patches-per-image N     Patches per image (default: 256)
-#   --detector TYPE           Detector: harris|fast|shi-tomasi|gradient (default: harris)
-#   --full-image              Use full-image training (disables patch mode)
-#   --image-size N            Image size for full-image mode (default: 256)
-#
-# DIRECTORIES:
-#   --input DIR               Input directory (default: training/input)
-#   --target DIR              Target directory (default: training/target_1)
-#   --checkpoint-dir DIR      Checkpoint directory (default: checkpoints)
-#   --validation-dir DIR      Validation directory (default: validation_results)
-#
-# OUTPUT:
-#   --output-weights PATH     Output binary weights file (default: workspaces/main/weights/cnn_v2_weights.bin)
-#
-# OTHER:
-#   --help                    Show this help message
-#
-# Examples:
-#   ./train_cnn_v2_full.sh
-#   ./train_cnn_v2_full.sh --epochs 500 --batch-size 32
-#   ./train_cnn_v2_full.sh --validate
-#   ./train_cnn_v2_full.sh --validate checkpoints/checkpoint_epoch_50.pth
-#   ./train_cnn_v2_full.sh --export-only checkpoints/checkpoint_epoch_100.pth
-#   ./train_cnn_v2_full.sh --mip-level 1 --kernel-sizes 3,5,3
-
-set -e
-
-PROJECT_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-cd "$PROJECT_ROOT"
-
-# Helper functions
-export_weights() {
-    python3 training/export_cnn_v2_weights.py "$1" --output-weights "$2" --quiet
-}
-
-find_latest_checkpoint() {
-    ls -t "$CHECKPOINT_DIR"/checkpoint_epoch_*.pth 2>/dev/null | head -1
-}
-
-build_target() {
-    cmake --build build -j4 --target "$1" > /dev/null 2>&1
-}
-
-# Default configuration
-INPUT_DIR="training/input"
-TARGET_DIR="training/target_1"
-CHECKPOINT_DIR="checkpoints"
-VALIDATION_DIR="validation_results"
-EPOCHS=200
-CHECKPOINT_EVERY=50
-BATCH_SIZE=16
-LEARNING_RATE=1e-3
-PATCH_SIZE=8
-PATCHES_PER_IMAGE=256
-DETECTOR="harris"
-KERNEL_SIZES="3,3,3"
-NUM_LAYERS=3
-MIP_LEVEL=0
-GRAYSCALE_LOSS=false
-FULL_IMAGE_MODE=false
-IMAGE_SIZE=256
-OUTPUT_WEIGHTS="workspaces/main/weights/cnn_v2_weights.bin"
-
-# Parse arguments
-VALIDATE_ONLY=false
-VALIDATE_CHECKPOINT=""
-EXPORT_ONLY=false
-EXPORT_CHECKPOINT=""
-
-if [ "$1" = "--help" ] || [ "$1" = "-h" ]; then
-    head -47 "$0" | grep "^#" | grep -v "^#!/" | sed 's/^# *//'
-    exit 0
-fi
-
-# Parse all arguments
-while [[ $# -gt 0 ]]; do
-    case "$1" in
-        --export-only)
-            EXPORT_ONLY=true
-            if [ -z "$2" ]; then
-                echo "Error: --export-only requires a checkpoint file argument"
-                exit 1
-            fi
-            EXPORT_CHECKPOINT="$2"
-            shift 2
-            ;;
-        --validate)
-            VALIDATE_ONLY=true
-            if [ -n "$2" ] && [[ ! "$2" =~ ^-- ]]; then
-                VALIDATE_CHECKPOINT="$2"
-                shift 2
-            else
-                shift
-            fi
-            ;;
-        --epochs)
-            if [ -z "$2" ]; then
-                echo "Error: --epochs requires a number argument"
-                exit 1
-            fi
-            EPOCHS="$2"
-            shift 2
-            ;;
-        --batch-size)
-            if [ -z "$2" ]; then
-                echo "Error: --batch-size requires a number argument"
-                exit 1
-            fi
-            BATCH_SIZE="$2"
-            shift 2
-            ;;
-        --checkpoint-every)
-            if [ -z "$2" ]; then
-                echo "Error: --checkpoint-every requires a number argument"
-                exit 1
-            fi
-            CHECKPOINT_EVERY="$2"
-            shift 2
-            ;;
-        --kernel-sizes)
-            if [ -z "$2" ]; then
-                echo "Error: --kernel-sizes requires a comma-separated list"
-                exit 1
-            fi
-            KERNEL_SIZES="$2"
-            shift 2
-            ;;
-        --num-layers)
-            if [ -z "$2" ]; then
-                echo "Error: --num-layers requires a number argument"
-                exit 1
-            fi
-            NUM_LAYERS="$2"
-            shift 2
-            ;;
-        --mip-level)
-            if [ -z "$2" ]; then
-                echo "Error: --mip-level requires a level argument (0-3)"
-                exit 1
-            fi
-            MIP_LEVEL="$2"
-            shift 2
-            ;;
-        --grayscale-loss)
-            GRAYSCALE_LOSS=true
-            shift
-            ;;
-        --lr)
-            if [ -z "$2" ]; then
-                echo "Error: --lr requires a float argument"
-                exit 1
-            fi
-            LEARNING_RATE="$2"
-            shift 2
-            ;;
-        --patch-size)
-            if [ -z "$2" ]; then
-                echo "Error: --patch-size requires a number argument"
-                exit 1
-            fi
-            PATCH_SIZE="$2"
-            shift 2
-            ;;
-        --patches-per-image)
-            if [ -z "$2" ]; then
-                echo "Error: --patches-per-image requires a number argument"
-                exit 1
-            fi
-            PATCHES_PER_IMAGE="$2"
-            shift 2
-            ;;
-        --detector)
-            if [ -z "$2" ]; then
-                echo "Error: --detector requires a type argument"
-                exit 1
-            fi
-            DETECTOR="$2"
-            shift 2
-            ;;
-        --full-image)
-            FULL_IMAGE_MODE=true
-            shift
-            ;;
-        --image-size)
-            if [ -z "$2" ]; then
-                echo "Error: --image-size requires a number argument"
-                exit 1
-            fi
-            IMAGE_SIZE="$2"
-            shift 2
-            ;;
-        --input)
-            if [ -z "$2" ]; then
-                echo "Error: --input requires a directory argument"
-                exit 1
-            fi
-            INPUT_DIR="$2"
-            shift 2
-            ;;
-        --target)
-            if [ -z "$2" ]; then
-                echo "Error: --target requires a directory argument"
-                exit 1
-            fi
-            TARGET_DIR="$2"
-            shift 2
-            ;;
-        --checkpoint-dir)
-            if [ -z "$2" ]; then
-                echo "Error: --checkpoint-dir requires a directory argument"
-                exit 1
-            fi
-            CHECKPOINT_DIR="$2"
-            shift 2
-            ;;
-        --validation-dir)
-            if [ -z "$2" ]; then
-                echo "Error: --validation-dir requires a directory argument"
-                exit 1
-            fi
-            VALIDATION_DIR="$2"
-            shift 2
-            ;;
-        --output-weights)
-            if [ -z "$2" ]; then
-                echo "Error: --output-weights requires a file path argument"
-                exit 1
-            fi
-            OUTPUT_WEIGHTS="$2"
-            shift 2
-            ;;
-        *)
-            echo "Unknown option: $1"
-            exit 1
-            ;;
-    esac
-done
-
-# Build training arguments
-if [ "$FULL_IMAGE_MODE" = true ]; then
-    TRAINING_MODE_ARGS="--full-image --image-size $IMAGE_SIZE"
-else
-    TRAINING_MODE_ARGS="--patch-size $PATCH_SIZE --patches-per-image $PATCHES_PER_IMAGE --detector $DETECTOR"
-fi
-
-# Handle export-only mode
-if [ "$EXPORT_ONLY" = true ]; then
-    echo "=== CNN v2 Export Weights Only ==="
-    echo "Checkpoint: $EXPORT_CHECKPOINT"
-    echo ""
-
-    if [ ! -f "$EXPORT_CHECKPOINT" ]; then
-        echo "Error: Checkpoint file not found: $EXPORT_CHECKPOINT"
-        exit 1
-    fi
-
-    export_weights "$EXPORT_CHECKPOINT" "$OUTPUT_WEIGHTS" || {
-        echo "Error: Export failed"
-        exit 1
-    }
-
-    echo ""
-    echo "=== Export Complete ==="
-    echo "Output: $OUTPUT_WEIGHTS"
-    exit 0
-fi
-
-if [ "$VALIDATE_ONLY" = true ]; then
-    echo "=== CNN v2 Validation Only ==="
-    echo "Skipping training, using existing weights"
-    echo ""
-else
-    echo "=== CNN v2 Complete Training Pipeline ==="
-    echo "Input: $INPUT_DIR"
-    echo "Target: $TARGET_DIR"
-    echo "Epochs: $EPOCHS"
-    echo "Checkpoint interval: $CHECKPOINT_EVERY"
-    echo "Mip level: $MIP_LEVEL (p0-p3 features)"
-    echo ""
-fi
-
-if [ "$VALIDATE_ONLY" = false ]; then
-    # Step 1: Train model
-    echo "[1/4] Training CNN v2 model..."
-
-python3 training/train_cnn_v2.py \
-  --input "$INPUT_DIR" \
-  --target "$TARGET_DIR" \
-  $TRAINING_MODE_ARGS \
-  --kernel-sizes "$KERNEL_SIZES" \
-  --num-layers "$NUM_LAYERS" \
-  --mip-level "$MIP_LEVEL" \
-  --epochs "$EPOCHS" \
-  --batch-size "$BATCH_SIZE" \
-  --lr "$LEARNING_RATE" \
-  --checkpoint-dir "$CHECKPOINT_DIR" \
-  --checkpoint-every "$CHECKPOINT_EVERY" \
-  $([ "$GRAYSCALE_LOSS" = true ] && echo "--grayscale-loss")
-
-if [ $? -ne 0 ]; then
-    echo "Error: Training failed"
-    exit 1
-fi
-
-echo ""
-echo "Training complete!"
-echo ""
-
-# Step 2: Export final checkpoint to shaders
-FINAL_CHECKPOINT="$CHECKPOINT_DIR/checkpoint_epoch_${EPOCHS}.pth"
-
-if [ ! -f "$FINAL_CHECKPOINT" ]; then
-    echo "Warning: Final checkpoint not found, using latest available..."
-    FINAL_CHECKPOINT=$(find_latest_checkpoint)
-fi
-
-if [ -z "$FINAL_CHECKPOINT" ] || [ ! -f "$FINAL_CHECKPOINT" ]; then
-    echo "Error: No checkpoint found in $CHECKPOINT_DIR"
-    exit 1
-fi
-
-echo "[2/4] Exporting final checkpoint to binary weights..."
-echo "Checkpoint: $FINAL_CHECKPOINT"
-export_weights "$FINAL_CHECKPOINT" "$OUTPUT_WEIGHTS" || {
-    echo "Error: Shader export failed"
-    exit 1
-}
-
-echo ""
-fi  # End of training/export section
-
-# Determine which checkpoint to use
-if [ "$VALIDATE_ONLY" = true ]; then
-    FINAL_CHECKPOINT="${VALIDATE_CHECKPOINT:-$(find_latest_checkpoint)}"
-    echo "Using checkpoint: $FINAL_CHECKPOINT"
-    echo ""
-fi
-
-# Step 3: Rebuild with new shaders
-if [ "$VALIDATE_ONLY" = false ]; then
-    echo "[3/4] Rebuilding demo with new shaders..."
-    build_target demo64k || {
-        echo "Error: Build failed"
-        exit 1
-    }
-    echo "  → Build complete"
-    echo ""
-fi
-
-# Step 4: Visual assessment - process final checkpoint only
-if [ "$VALIDATE_ONLY" = true ]; then
-    echo "Validation on all input images (using existing weights)..."
-else
-    echo "[4/4] Visual assessment on all input images..."
-fi
-
-mkdir -p "$VALIDATION_DIR"
-echo "  Using checkpoint: $FINAL_CHECKPOINT"
-
-# Export weights for validation mode (already exported in step 2 for training mode)
-if [ "$VALIDATE_ONLY" = true ]; then
-    export_weights "$FINAL_CHECKPOINT" "$OUTPUT_WEIGHTS" > /dev/null 2>&1
-fi
-
-# Build cnn_test
-build_target cnn_test
-
-# Process all input images
-echo -n "  Processing images: "
-for input_image in "$INPUT_DIR"/*.png; do
-    basename=$(basename "$input_image" .png)
-    echo -n "$basename "
-    build/cnn_test "$input_image" "$VALIDATION_DIR/${basename}_output.png" --weights "$OUTPUT_WEIGHTS" > /dev/null 2>&1
-done
-echo "✓"
-
-# Build demo only if not in validate mode
-[ "$VALIDATE_ONLY" = false ] && build_target demo64k
-
-echo ""
-if [ "$VALIDATE_ONLY" = true ]; then
-    echo "=== Validation Complete ==="
-else
-    echo "=== Training Pipeline Complete ==="
-fi
-echo ""
-echo "Results:"
-if [ "$VALIDATE_ONLY" = false ]; then
-    echo "  - Checkpoints: $CHECKPOINT_DIR"
-    echo "  - Final weights: $OUTPUT_WEIGHTS"
-fi
-echo "  - Validation outputs: $VALIDATION_DIR"
-echo ""
-echo "Opening results directory..."
-open "$VALIDATION_DIR" 2>/dev/null || xdg-open "$VALIDATION_DIR" 2>/dev/null || true
-
-if [ "$VALIDATE_ONLY" = false ]; then
-    echo ""
-    echo "Run demo to see final result:"
-    echo "  ./build/demo64k"
-fi