Enable training on XPU using SingleXPUStrategy

Setting the SingleXPUStrategy fixes the error message,
```
Failed to train pending training job: Device should be xpu, got cpu
instead
```

After this another error would show up,
```
Cannot re-initialize XPU in forked subproces. To use XPU with
multiprocessing you must use the `spawn` method
```

This requires us to set the start method of our `main.py` file.

Signed-off-by: Mark Redeman <[email protected]>

Author: MarkRedeman

application/backend/src/main.py

@@ -1,6 +1,11 @@
 # Copyright (C) 2025 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
+import multiprocessing as mp
+
+if mp.get_start_method(allow_none=True) != "spawn":
+    mp.set_start_method("spawn", force=True)
+
 import os
 
 import uvicorn

application/backend/src/services/training_service.py

@@ -9,6 +9,7 @@
 from anomalib.data.utils import ValSplitMode
 from anomalib.deploy import ExportType
 from anomalib.engine import Engine
+from anomalib.engine.strategy.xpu_single import SingleXPUStrategy
 from anomalib.loggers import AnomalibTensorBoardLogger
 from anomalib.models import get_model
 from loguru import logger
@@ -214,6 +215,7 @@ def _train_model(
             max_epochs=max_epochs,
             callbacks=[GetiInspectProgressCallback(synchronization_parameters)],
             accelerator=training_device,
+            **({"strategy": SingleXPUStrategy()} if training_device == "xpu" else {}),
         )
 
         # Execute training and export