fix: resolve ONNX CUDA fallback, Docker e2e infrastructure, and all test failures

- Add safe_onnx_session() to gpu.py with graceful CUDA EP → CPU fallback
- Replace bare ort.InferenceSession() calls across colorize, restore, inpaint, remove_bg
- Add libcublas-12-6 to production Dockerfile for ONNX Runtime CUDA EP
- Add skipIfFeatureNotInstalled guards to remove-bg, blur-faces, smart-crop, ocr, noise-removal e2e specs
- Add AI tool install prompt detection in tools-all.spec.ts
- Add smart-crop to PYTHON_SIDECAR_TOOLS so frontend shows install prompt correctly
- Create Dockerfile.test.dockerignore to include tests/ in test image builds
- Add libheif-examples and exiftool to Dockerfile.test for HEIC and metadata tests
- Regenerate visual regression baselines for Docker/Linux and skip on non-Docker platforms

packages/ai/python/gpu.py

@@ -55,3 +55,20 @@ def onnx_providers():
     if gpu_available():
         return ["CUDAExecutionProvider", "CPUExecutionProvider"]
     return ["CPUExecutionProvider"]
+
+
+def safe_onnx_session(model_path, providers=None):
+    """Create an ONNX Runtime InferenceSession with graceful CUDA EP fallback."""
+    import onnxruntime as ort
+
+    if providers is None:
+        providers = onnx_providers()
+
+    try:
+        return ort.InferenceSession(model_path, providers=providers)
+    except Exception as e:
+        if "CUDAExecutionProvider" in providers:
+            print(f"[gpu] CUDA EP init failed ({e}), falling back to CPU",
+                  file=sys.stderr, flush=True)
+            return ort.InferenceSession(model_path, providers=["CPUExecutionProvider"])
+        raise