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, 89 deletions

diff --git a/src/effects/cnn_v2_effect.h b/src/effects/cnn_v2_effect.h
deleted file mode 100644
index 7960b4f..0000000
--- a/src/effects/cnn_v2_effect.h
+++ /dev/null
@@ -1,89 +0,0 @@
-// CNN v2 Effect - Parametric Static Features
-// Multi-pass post-processing with 7D feature input
-// Supports per-layer kernel sizes (e.g., 1×1, 3×3, 5×5)
-
-#pragma once
-#include "gpu/effect.h"
-#include <vector>
-
-struct CNNv2EffectParams {
-  float blend_amount = 1.0f;
-};
-
-class CNNv2Effect : public PostProcessEffect {
- public:
-  explicit CNNv2Effect(const GpuContext& ctx);
-  explicit CNNv2Effect(const GpuContext& ctx, const CNNv2EffectParams& params);
-  ~CNNv2Effect();
-
-  void init(MainSequence* demo) override;
-  void resize(int width, int height) override;
-  void compute(WGPUCommandEncoder encoder,
-               const CommonPostProcessUniforms& uniforms) override;
-  void render(WGPURenderPassEncoder pass,
-              const CommonPostProcessUniforms& uniforms) override;
-  void update_bind_group(WGPUTextureView input_view) override;
-
-  void set_beat_modulation(bool enabled, float scale = 1.0f) {
-    beat_modulated_ = enabled;
-    beat_scale_ = scale;
-  }
-
- private:
-  struct LayerInfo {
-    uint32_t kernel_size;
-    uint32_t in_channels;
-    uint32_t out_channels;
-    uint32_t weight_offset;
-    uint32_t weight_count;
-  };
-
-  struct LayerParams {
-    uint32_t kernel_size;
-    uint32_t in_channels;
-    uint32_t out_channels;
-    uint32_t weight_offset;
-    uint32_t is_output_layer;
-    float blend_amount;
-    uint32_t is_layer_0;
-  };
-
-  struct StaticFeatureParams {
-    uint32_t mip_level;
-    uint32_t padding[3];
-  };
-
-  void create_textures();
-  void create_pipelines();
-  void load_weights();
-  void cleanup();
-
-  // Static features compute
-  WGPUComputePipeline static_pipeline_;
-  WGPUBindGroup static_bind_group_;
-  WGPUBuffer static_params_buffer_;
-  WGPUTexture static_features_tex_;
-  WGPUTextureView static_features_view_;
-  WGPUSampler linear_sampler_;
-
-  // CNN layers (storage buffer architecture)
-  WGPUComputePipeline layer_pipeline_; // Single pipeline for all layers
-  WGPUBuffer weights_buffer_;          // Storage buffer for weights
-  std::vector<WGPUBuffer>
-      layer_params_buffers_;          // Uniform buffers (one per layer)
-  std::vector<LayerInfo> layer_info_; // Layer metadata
-  std::vector<WGPUBindGroup> layer_bind_groups_; // Per-layer bind groups
-  std::vector<WGPUTexture> layer_textures_;      // Ping-pong buffers
-  std::vector<WGPUTextureView> layer_views_;
-
-  // Input mips
-  WGPUTexture input_mip_tex_;
-  WGPUTextureView input_mip_view_[3];
-  WGPUTextureView current_input_view_;
-
-  float blend_amount_ = 1.0f;
-  bool beat_modulated_ = false;
-  float beat_scale_ = 1.0f;
-  uint32_t mip_level_ = 0;
-  bool initialized_;
-};