Initialize legacy kernels compatibility mirror

Add manual_attention_part_hp (fp32-logits variant)

Restore package README; record v2 verdict and structural downgrade

Record v2 end-to-end verdict and structural-split downgrade in RESULTS

Add manual_attention_part_v2 (bf16-saved-p, fused softmax gradient)

Add package source and torch-universal build variant

Initialize legacy kernels compatibility mirror

initial commit