Use prebuilt image for dashboard stack

apps/dashboard/.env.example

@@ -1,4 +1,5 @@
-APP_ENV=production
+DASHBOARD_IMAGE=
+APP_ENV=production
 APP_HOST=0.0.0.0
 APP_PORT=8000
 APP_LOG_LEVEL=INFO
@@ -19,3 +20,4 @@ UPTIME_KUMA_USERNAME=
 UPTIME_KUMA_PASSWORD=
 HOME_ASSISTANT_BASE_URL=http://192.168.178.50:8123
 HOME_ASSISTANT_TOKEN=
+

apps/dashboard/docker-compose.yml

@@ -1,9 +1,6 @@
 services:
   dashboard:
-    build:
-      context: .
-      dockerfile: Dockerfile
-      network: host
+    image: ${DASHBOARD_IMAGE}
     container_name: kallilab-dashboard
     restart: unless-stopped
     environment:
@@ -46,3 +43,4 @@ networks:
   frontend_net:
     external: true
 
+