merge: lane/engine-hardening-20260819 @ d8fb006489 — unknown GGUF pretokenizer is a hard load error (gemma-4's absent `pre` explicitly allowlisted after a tensor-census audit), attn_out_gate() per-arch exhaustive declaration + read-site bounds check (compute-sanitizer: 51 invalid reads before, 0 after). Lane owed the perf battery; this train runs it.