Fix service DNS by using explicit named network

network_mode: bridge uses Docker's default bridge which has no
service-name DNS. An explicit named network gets its own resolver
so nginx can resolve "server" by name. Also adds a healthcheck so
app waits until server is actually ready before nginx starts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -12,15 +12,30 @@ services:
       - OLLAMA_MODEL=${OLLAMA_MODEL:-gemma4:latest}
     extra_hosts:
       - "host-gateway:host-gateway"
+    networks:
+      - internal
+    healthcheck:
+      test: ["CMD-SHELL", "node -e \"require('net').createConnection(3000).on('connect',()=>process.exit(0)).on('error',()=>process.exit(1))\""]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+      start_period: 15s
 
   app:
     build: ./frontend
     restart: unless-stopped
     depends_on:
-      - server
+      server:
+        condition: service_healthy
+    networks:
+      - internal
     ports:
       - "127.0.0.1:3080:80"
 
+networks:
+  internal:
+    driver: bridge
+
 volumes:
   server_data:
   server_uploads: