docs : fix Metal backend op support status in ops.md (#20779)
Regenerate docs/ops/Metal.csv using test-backend-ops on Apple M5
and rebuild docs/ops.md via scripts/create_ops_docs.py.
Five ops were incorrectly marked as not supported (❌) for Metal:
- DIAG: ❌ → ✅
- POOL_1D: ❌ → ✅
- SET: ❌ → ✅
- SOLVE_TRI: ❌ → ✅
- GATED_DELTA_NET:❌ → 🟡 (partial, depends on head_size % 32)
