fix: remove public backend domain that always returned 404

The Multica backend is an API-only chi server with no route registered
at "/", so the generated backend domain (path "/") permanently answered
HTTP 404 even though the container was healthy. The web frontend already
proxies /api/*, /ws, /auth/* and /uploads/* to http://backend:8080 via
Next.js rewrites, and when NEXT_PUBLIC_WS_URL is unset the browser
derives the WebSocket URL from the page origin, so the backend never
needs to be exposed publicly.

- drop the backend [[config.domains]] entry and api_domain variable
- drop NEXT_PUBLIC_WS_URL so the WS URL falls back to the page origin
  and goes through the frontend's /ws rewrite
- remove ephemeral host port publications (ports: "8080"/"3000");
  Traefik reaches the containers over the docker network

Verified on a Dokploy instance: deploy done, frontend / -> 200 and
backend reachable through the proxy (/api/config -> 200).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

blueprints/multica/docker-compose.yml

@@ -24,8 +24,6 @@ services:
     depends_on:
       postgres:
         condition: service_healthy
-    ports:
-      - "8080"
     volumes:
       - backend_uploads:/app/data/uploads
     environment:
@@ -53,13 +51,10 @@ services:
       dockerfile: Dockerfile.web
       args:
         REMOTE_API_URL: http://backend:8080
-        NEXT_PUBLIC_WS_URL: ${NEXT_PUBLIC_WS_URL}
         NEXT_PUBLIC_GOOGLE_CLIENT_ID: ${NEXT_PUBLIC_GOOGLE_CLIENT_ID}
     restart: unless-stopped
     depends_on:
       - backend
-    ports:
-      - "3000"
     environment:
       HOSTNAME: "0.0.0.0"
 

blueprints/multica/template.toml

@@ -1,6 +1,5 @@
 [variables]
 app_domain = "${domain}"
-api_domain = "${domain}"
 jwt_secret = "${password:64}"
 postgres_password = "${password:32}"
 
@@ -11,12 +10,6 @@ port = 3000
 host = "${app_domain}"
 path = "/"
 
-[[config.domains]]
-serviceName = "backend"
-port = 8080
-host = "${api_domain}"
-path = "/"
-
 [config.env]
 POSTGRES_DB = "multica"
 POSTGRES_USER = "multica"
@@ -25,7 +18,6 @@ JWT_SECRET = "${jwt_secret}"
 FRONTEND_ORIGIN = "https://${app_domain}"
 ALLOWED_ORIGINS = "https://${app_domain}"
 MULTICA_APP_URL = "https://${app_domain}"
-NEXT_PUBLIC_WS_URL = "wss://${api_domain}/ws"
 RESEND_API_KEY = ""
 RESEND_FROM_EMAIL = "noreply@multica.ai"
 GOOGLE_CLIENT_ID = ""