chore: OpenVINO MetricGAN GPU spike (do not merge)

Arc B580 lost the kill test: batch-14 mask p50 103 ms vs Torch CPU
70 ms enhance / OpenVINO CPU 5 ms. Production stays on known-good
CPU workers (tag known-good-cpu-2026-08-28). Hop stays 200 ms.

scripts/spike_dump_metricgan.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""Dump MetricGAN enhance_model I/O so the OpenVINO spike can convert it."""
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
+
+import torch
+from speechbrain.inference.enhancement import SpectralMaskEnhancement
+
+SAVEDIR = "/root/.cache/speechbrain-enhancement"
+
+
+def main() -> None:
+    m = SpectralMaskEnhancement.from_hparams(
+        source="speechbrain/metricgan-plus-voicebank",
+        savedir=SAVEDIR,
+        run_opts={"device": "cpu"},
+    )
+    net = m.mods.enhance_model
+    print("enhance_model", type(net).__name__)
+    print("device", m.device)
+    wav = torch.randn(1, 16000)
+    feats = m.compute_features(wav)
+    print("wav", tuple(wav.shape), "feats", tuple(feats.shape), feats.dtype)
+    lengths = torch.tensor([1.0])
+    with torch.no_grad():
+        mask = net(feats, lengths=lengths)
+    print("mask", tuple(mask.shape), mask.dtype)
+    print("modules:")
+    for name, mod in net.named_children():
+        print(f"  {name}: {type(mod).__name__}")
+
+
+if __name__ == "__main__":
+    main()