fix: Support variable kernel sizes in CNN layer generation

Training script was hardcoded to generate cnn_conv3x3_* calls regardless
of actual kernel size, causing shader validation errors when layer 1 used
5×5 kernel (100 weights) but called 3×3 function (expected 36).

Changes:
- train_cnn.py: Generate correct conv function based on kernel_sizes[i]
- cnn_conv5x5.wgsl: Add cnn_conv5x5_7to4 and cnn_conv5x5_7to1 variants
- Regenerate cnn_layer.wgsl with correct function calls for [3,5,3]
- Document kernel size→function mapping in HOWTO.md

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

0 files changed, 0 insertions, 0 deletions