CNN v2: Refactor to uniform 12D→4D architecture

**Architecture changes:**
- Static features (8D): p0-p3 (parametric) + uv_x, uv_y, sin(10×uv_x), bias
- Input RGBD (4D): fed separately to all layers
- All layers: uniform 12D→4D (4 prev/input + 8 static → 4 output)
- Bias integrated in static features (bias=False in PyTorch)

**Weight calculations:**
- 3 layers × (12 × 3×3 × 4) = 1296 weights
- f16: 2.6 KB (vs old variable arch: ~6.4 KB)

**Updated files:**

*Training (Python):*
- train_cnn_v2.py: Uniform model, takes input_rgbd + static_features
- export_cnn_v2_weights.py: Binary export for storage buffers
- export_cnn_v2_shader.py: Per-layer shader export (debugging)

*Shaders (WGSL):*
- cnn_v2_static.wgsl: p0-p3 parametric features (mips/gradients)
- cnn_v2_compute.wgsl: 12D input, 4D output, vec4 packing

*Tools:*
- HTML tool (cnn_v2_test): Updated for 12D→4D, layer visualization

*Docs:*
- CNN_V2.md: Updated architecture, training, validation sections
- HOWTO.md: Reference HTML tool for validation

*Removed:*
- validate_cnn_v2.sh: Obsolete (used CNN v1 tool)

All code consistent with bias=False (bias in static features as 1.0).

handoff(Claude): CNN v2 architecture finalized and documented

1 files changed, 0 insertions, 60 deletions

diff --git a/scripts/validate_cnn_v2.sh b/scripts/validate_cnn_v2.sh
deleted file mode 100755
index 06a4e01..0000000
--- a/scripts/validate_cnn_v2.sh
+++ /dev/null
@@ -1,60 +0,0 @@
-#!/bin/bash
-# CNN v2 Validation - End-to-end pipeline
-
-set -e
-PROJECT_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-BUILD_DIR="$PROJECT_ROOT/build"
-WORKSPACE="main"
-
-usage() {
-    echo "Usage: $0 <checkpoint.pth> [options]"
-    echo "Options:"
-    echo "  -i DIR    Test images (default: training/validation)"
-    echo "  -o DIR    Output (default: validation_results)"
-    echo "  --skip-build    Skip rebuild"
-    exit 1
-}
-
-[ $# -eq 0 ] && usage
-CHECKPOINT="$1"
-shift
-
-TEST_IMAGES="$PROJECT_ROOT/training/validation"
-OUTPUT="$PROJECT_ROOT/validation_results"
-SKIP_BUILD=false
-
-while [[ $# -gt 0 ]]; do
-    case $1 in
-        -i) TEST_IMAGES="$2"; shift 2 ;;
-        -o) OUTPUT="$2"; shift 2 ;;
-        --skip-build) SKIP_BUILD=true; shift ;;
-        -h) usage ;;
-        *) usage ;;
-    esac
-done
-
-echo "=== CNN v2 Validation ==="
-echo "Checkpoint: $CHECKPOINT"
-
-# Export
-echo "[1/3] Exporting shaders..."
-python3 "$PROJECT_ROOT/training/export_cnn_v2_shader.py" "$CHECKPOINT" \
-    --output-dir "$PROJECT_ROOT/workspaces/$WORKSPACE/shaders"
-
-# Build
-if [ "$SKIP_BUILD" = false ]; then
-    echo "[2/3] Building..."
-    cmake --build "$BUILD_DIR" -j4 --target cnn_test >/dev/null 2>&1
-fi
-
-# Process
-echo "[3/3] Processing images..."
-mkdir -p "$OUTPUT"
-count=0
-for img in "$TEST_IMAGES"/*.png; do
-    [ -f "$img" ] || continue
-    name=$(basename "$img" .png)
-    "$BUILD_DIR/cnn_test" "$img" "$OUTPUT/${name}_output.png" 2>/dev/null && count=$((count+1))
-done
-
-echo "Done! Processed $count images → $OUTPUT"