bake sentence transformer model into Docker image to fix init network error

SentenceTransformer('all-MiniLM-L6-v2') was downloading at runtime during
startup, failing because HF Spaces containers can't reach huggingface.co
during the init phase. Pre-downloading at build time avoids the network call.

Made-with: Cursor

Dockerfile

@@ -26,6 +26,10 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY backend/requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
+# Pre-download the sentence transformer model into the image
+# so startup doesn't require network access to huggingface.co
+RUN python -c "from sentence_transformers import SentenceTransformer; SentenceTransformer('all-MiniLM-L6-v2')"
+
 # Copy backend
 COPY --chown=user backend/ /app/backend/