deploy: support configurable backend host for frontend API URL

.gitea/workflows/deploy.yml

@@ -18,6 +18,7 @@ jobs:
         run: |
           cat > .env.production << 'ENVEOF'
           DOMAIN=${{ secrets.DOMAIN }}
+          BACKEND_HOST=${{ secrets.BACKEND_HOST }}
           FRONTEND_HOST=${{ secrets.FRONTEND_HOST }}
           ENVIRONMENT=production
           PROJECT_NAME=${{ secrets.PROJECT_NAME }}

compose.prod.yml

@@ -81,7 +81,7 @@ services:
       context: .
       dockerfile: frontend/Dockerfile
       args:
-        - VITE_API_URL=https://api.${DOMAIN?Variable not set}
+        - VITE_API_URL=https://${BACKEND_HOST:-api.${DOMAIN?Variable not set}}
         - NODE_ENV=production
 
 networks: