Fix: Add frontend to app-network for backend connectivity

- Frontend now connects to both app-network and caddy_network
- Resolves network isolation preventing API calls to backend
- Fixes document upload functionality by enabling frontend→backend communication

docker-compose.yml

@@ -15,6 +15,7 @@ services:
     depends_on:
       - backend
     networks:
+      - app-network
       - caddy_network
 
   backend: