Install torchvision from CPU index to match torch

Dockerfile

@@ -21,9 +21,12 @@ ENV HOME=/home/user \
 
 WORKDIR /home/user/app
 
-# Install CPU-only PyTorch first (smaller, no CUDA), then the rest
+# Install CPU-only PyTorch + torchvision FIRST, both from the CPU index so their
+# compiled ops match. (If torchvision comes from default PyPI it's the CUDA build
+# and fails at runtime with "operator torchvision::nms does not exist".)
 RUN pip install --no-cache-dir --upgrade pip && \
-    pip install --no-cache-dir torch==2.7.1 --index-url https://download.pytorch.org/whl/cpu
+    pip install --no-cache-dir torch==2.7.1 torchvision==0.22.1 \
+        --index-url https://download.pytorch.org/whl/cpu
 
 # Dependency layer (cached unless requirements.txt changes)
 COPY --chown=user requirements.txt .