CRITICAL BUG: P was stored using QK C-fragment composition layout, but PV
A-fragment reads using p_tmem_s.outer (PV A-operand layout). These layouts
match at hd=64 (cos 0.999998) but diverge at hd>64 (cos 0.784 at hd=128).
The fix: tStP0 and tScP now use p_tmem_s.outer instead of
composition(tStS.layout, (128, p_cols_fp32)). This ensures the softmax
writes P in the same layout that the PV GEMM expects.
biondizzle
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