fix(compose): connect app to coolify network so Traefik can route traffic

Coolify's Traefik is on the 'coolify' Docker network. Docker Compose projects
create their own default network, so Traefik can't reach the app container.
Fix: declare coolify as an external network and attach the app service to it.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

compose.coolify.yml

@@ -21,6 +21,9 @@ services:
       JWT_SECRET: ${JWT_SECRET}
       # CORS allowed origins
       ALLOWED_ORIGINS: ${ALLOWED_ORIGINS:-https://agenthub.barodine.net}
+    networks:
+      - default
+      - coolify
     depends_on:
       postgres:
         condition: service_healthy
@@ -146,3 +149,5 @@ networks:
   default:
     labels:
       - 'coolify.managed=true'
+  coolify:
+    external: true