- Document flat_group_gemm_fuse_reshape and softmax_fuse_block_sum kernels
- Explain anti-diagonal sum principle and stride sampling
- Add GPU-specific BLOCK_M/N constraints (RTX 3090 vs A100)
- Show Q/K can have different lengths (chunked prefill support)
- Update CLAUDE.md with doc reference
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
