chore: update Dockerfile permissions and modify start.sh to change directory before starting backend

Dockerfile

@@ -49,7 +49,8 @@ COPY --from=backend /usr/local/lib/python3.9/site-packages /usr/local/lib/python
 # 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
+    chmod -R 755 /app/backend && \
+    chmod 755 /app/generated_images
 
 COPY start.sh .
 RUN chmod +x start.sh

start.sh

@@ -1,5 +1,6 @@
 #!/bin/sh
 # Start frontend in background
 node frontend/server.js &
-# Start backend
+# Start backend from /app directory so it can find generated_images
+cd /app
 python -m uvicorn backend.app.main:app --host 0.0.0.0 --port 8000