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, 3 insertions, 3 deletions

diff --git a/workspaces/main/assets.txt b/workspaces/main/assets.txt
index 972cc8b..e1cf2bc 100644
--- a/workspaces/main/assets.txt
+++ b/workspaces/main/assets.txt
@@ -44,9 +44,9 @@ SHADER_CNN_CONV5X5, NONE, shaders/cnn/cnn_conv5x5.wgsl, "CNN 5x5 Convolution"
 SHADER_CNN_CONV7X7, NONE, shaders/cnn/cnn_conv7x7.wgsl, "CNN 7x7 Convolution"
 SHADER_CNN_WEIGHTS, NONE, shaders/cnn/cnn_weights_generated.wgsl, "CNN Weights (Generated)"
 SHADER_CNN_LAYER, NONE, shaders/cnn/cnn_layer.wgsl, "CNN Layer Shader"
-SHADER_CNN_V2_STATIC, NONE, shaders/cnn_v2/cnn_v2_static.wgsl, "CNN v2 Static Features"
-SHADER_CNN_V2_COMPUTE, NONE, shaders/cnn_v2/cnn_v2_compute.wgsl, "CNN v2 Compute (Storage Buffer)"
-WEIGHTS_CNN_V2, NONE, weights/cnn_v2_weights.bin, "CNN v2 Binary Weights"
+SHADER_CNN_V2_STATIC, NONE, ../../cnn_v2/shaders/cnn_v2_static.wgsl, "CNN v2 Static Features"
+SHADER_CNN_V2_COMPUTE, NONE, ../../cnn_v2/shaders/cnn_v2_compute.wgsl, "CNN v2 Compute (Storage Buffer)"
+WEIGHTS_CNN_V2, NONE, ../../cnn_v2/weights/cnn_v2_weights.bin, "CNN v2 Binary Weights"
 SHADER_SOLARIZE, NONE, shaders/solarize.wgsl, "Solarize Shader"
 SHADER_DISTORT, NONE, shaders/distort.wgsl, "Distort Shader"
 SHADER_CHROMA_ABERRATION, NONE, shaders/chroma_aberration.wgsl, "Chroma Aberration Shader"