Connect web service to Coolify's Traefik proxy network

Without joining the external 'coolify' network, Traefik cannot reach
the container and the reverse proxy returns 502.

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

docker-compose.yaml

@@ -2,8 +2,8 @@ services:
   web:
     build: .
     container_name: cot_web
-    ports:
-      - "31478:8000"
+    expose:
+      - "8000"
     volumes:
       - cot_data:/data
     environment:
@@ -18,6 +18,9 @@ services:
       timeout: 10s
       retries: 3
       start_period: 10s
+    networks:
+      - coolify
+      - default
 
   cron:
     build: .
@@ -31,7 +34,13 @@ services:
     depends_on:
       web:
         condition: service_healthy
+    networks:
+      - default
 
 volumes:
   cot_data:
     driver: local
+
+networks:
+  coolify:
+    external: true