部署迁移：VPS 本机构建 → GitHub Actions 构建镜像推送 ghcr.io

CI 新增 build-and-push job，测试通过后构建 backend/frontend 镜像推送 ghcr.io。
VPS 部署改为 docker compose pull + up -d，不再本地编译。

docker-compose.yml

@@ -1,6 +1,5 @@
 services:
   polyweather:
-    build: .
     container_name: polyweather_bot
     cpus: ${POLYWEATHER_BOT_CPUS:-0.75}
     env_file: &id001
@@ -18,7 +17,7 @@ services:
       - import sqlite3; c=sqlite3.connect('/var/lib/polyweather/polyweather.db');
         c.execute('SELECT 1'); c.close()
       timeout: 10s
-    image: polyweather-app:latest
+    image: ghcr.io/yangyuan-zhen/polyweather-backend:latest
     mem_limit: ${POLYWEATHER_BOT_MEM_LIMIT:-768m}
     memswap_limit: ${POLYWEATHER_BOT_MEMSWAP_LIMIT:-1g}
     pids_limit: 256
@@ -29,15 +28,6 @@ services:
     - ${POLYWEATHER_RUNTIME_DATA_DIR:-/var/lib/polyweather}:/app/data
     - ./bot.log:/app/bot.log
   polyweather_frontend:
-    build:
-      args:
-        NEXT_PUBLIC_POLYWEATHER_API_BASE_URL: https://api.polyweather.top
-        NEXT_PUBLIC_POLYWEATHER_LOCAL_FULL_ACCESS: 'false'
-        NEXT_PUBLIC_SITE_URL: https://polyweather.top
-        NEXT_PUBLIC_SUPABASE_ANON_KEY: ''
-        NEXT_PUBLIC_SUPABASE_URL: ''
-      context: ./frontend
-      dockerfile: Dockerfile
     container_name: polyweather_frontend
     environment:
       NEXT_PUBLIC_POLYWEATHER_API_BASE_URL: ${NEXT_PUBLIC_POLYWEATHER_API_BASE_URL:-}
@@ -57,11 +47,11 @@ services:
       - -qO-
       - http://localhost:3000
       timeout: 5s
+    image: ghcr.io/yangyuan-zhen/polyweather-frontend:latest
     ports:
     - 3001:3000
     restart: unless-stopped
   polyweather_web:
-    build: .
     command: python web/app.py
     container_name: polyweather_web
     env_file: *id001
@@ -74,7 +64,7 @@ services:
       - -c
       - from urllib.request import urlopen; urlopen('http://localhost:8000/healthz')
       timeout: 5s
-    image: polyweather-app:latest
+    image: ghcr.io/yangyuan-zhen/polyweather-backend:latest
     ports:
     - 8000:8000
     restart: unless-stopped
@@ -83,6 +73,5 @@ services:
     - ${POLYWEATHER_RUNTIME_DATA_DIR:-/var/lib/polyweather}:/var/lib/polyweather
     - ${POLYWEATHER_RUNTIME_DATA_DIR:-/var/lib/polyweather}:/app/data
 x-polyweather-base:
-  build: .
   env_file: *id001
-  image: polyweather-app:latest
+  image: ghcr.io/yangyuan-zhen/polyweather-backend:latest