chore: create directories for generated images and set permissions in Dockerfile; update start.sh to run frontend and backend as nextjs user

Dockerfile

@@ -46,6 +46,11 @@ COPY --from=frontend-builder --chown=nextjs:nodejs /app/.next/cache ./frontend/.
 COPY --from=backend /backend ./backend
 COPY --from=backend /usr/local/lib/python3.9/site-packages /usr/local/lib/python3.9/site-packages
 
+# Create directories and set permissions
+RUN mkdir -p /app/generated_images && \
+    chown -R nextjs:nodejs /app/backend /app/generated_images && \
+    chmod -R 755 /app/backend /app/generated_images
+
 COPY start.sh .
 RUN chmod +x start.sh
 

start.sh

@@ -1,3 +1,5 @@
 #!/bin/sh
-node frontend/server.js &
-python -m uvicorn backend.app.main:app --host 0.0.0.0 --port 8000
+# Start frontend as nextjs user
+su nextjs -c "node frontend/server.js" &
+# Start backend as nextjs user
+su nextjs -c "python -m uvicorn backend.app.main:app --host 0.0.0.0 --port 8000"