Add MIGraphX/half deps and use AMD onnxruntime wheel for ROCm 6.1.3

Per AMD docs (rocm.docs.amd.com install-onnx):
- apt install migraphx, migraphx-dev, half (required by onnxruntime-rocm)
- Switch to AMD-hosted wheel: onnxruntime_rocm-1.17.0-cp310 from repo.radeon.com
- Pin numpy==1.26.4 (numpy 2.0 incompatible with this wheel)
- Add MIGraphXExecutionProvider to provider list in engine.py

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

engine.py

@@ -37,7 +37,11 @@ def detect_device() -> str:
 
 def _get_providers(device: str) -> list:
     if device in ("rocm", "cuda"):
-        return [("ROCMExecutionProvider", {"device_id": 0}), "CPUExecutionProvider"]
+        return [
+            "MIGraphXExecutionProvider",
+            ("ROCMExecutionProvider", {"device_id": 0}),
+            "CPUExecutionProvider",
+        ]
     return ["CPUExecutionProvider"]