fix: dashboard API proxy - use server-side rewrite instead of client-side URL

docker-compose.yml

@@ -65,7 +65,8 @@ services:
     ports:
       - "3000:3000"
     environment:
-      - NEXT_PUBLIC_API_URL=http://localhost:8080
+      - NEXT_PUBLIC_API_URL=
+      - API_URL=http://server:8080
       - NODE_ENV=production
     depends_on:
       - server