Match Qwen head-chunked attention execution

docs/issue113-head-chunk/plan.log

@@ -0,0 +1,5 @@
+
+running 1 test
+test engine::metal::qwen_mtplx::verify_sdpa::issue113_plan_and_policy_match_pinned_oracle ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 548 filtered out; finished in 0.00s