Add portfolio app to proxy network

- Add proxy network to portfolio service networks
- Define proxy as external network in Docker Compose
- This allows the application to be accessible through the proxy network
- Fixes the 'Main page is not accessible' issue

The portfolio app will now be on both portfolio_net (for internal communication) and proxy (for external access).

docker-compose.yml

@@ -22,6 +22,7 @@ services:
       - portfolio_data:/app/.next/cache
     networks:
       - portfolio_net
+      - proxy
     depends_on:
       postgres:
         condition: service_healthy
@@ -95,3 +96,5 @@ volumes:
 networks:
   portfolio_net:
     driver: bridge
+  proxy:
+    external: true