Fix Hugging Face cache permissions

- Set HF_HOME, TRANSFORMERS_CACHE, HF_HUB_CACHE to /data/huggingface
- Create all required cache directories with proper permissions
- Fixes RuntimeError: Data processing error: I/O error: Permission denied

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Dockerfile

@@ -9,8 +9,14 @@ ENV MODEL_FILENAME=phi4-mini-instruct-Q4_K_M.gguf
 ENV USE_RAG=true
 ENV CACHE_ENABLED=true
 
-# Ensure /data and /app/models directories exist and are writable
-RUN mkdir -p /data /app/models && chmod -R 777 /data /app/models
+# Set Hugging Face cache to /data for persistence and write permissions
+ENV HF_HOME=/data/huggingface
+ENV TRANSFORMERS_CACHE=/data/huggingface/transformers
+ENV HF_HUB_CACHE=/data/huggingface/hub
+
+# Ensure all required directories exist and are writable
+RUN mkdir -p /data /app/models /data/huggingface/hub /data/huggingface/transformers && \
+    chmod -R 777 /data /app/models
 
 EXPOSE 8000
 CMD ["python", "main.py"]