完全移除预热（prewarm）功能

- 删除 src/utils/prewarm_dashboard.py
- 删除 scripts/prewarm_dashboard_cache.py、prewarm_dashboard_worker.py
- docker-compose.yml 移除 polyweather_prewarm 服务
- runtime_coordinator.py 移除预热循环启动逻辑
- web/core.py 移除 prewarm status 上报
- web/routers/system.py 移除 /api/system/prewarm 端点
- web/services/system_api.py 移除 run_system_prewarm
- city_runtime.py DEFAULT_PREWARM_CITIES 改名为 DEFAULT_STATUS_CITIES
- 清理 env.example、测试、VPS .env 中的预热配置

web/services/city_runtime.py

@@ -80,7 +80,7 @@ TRACKABLE_ANALYTICS_EVENTS = {
     "checkout_succeeded",
 }
 
-DEFAULT_PREWARM_CITIES = [
+DEFAULT_STATUS_CITIES = [
     "ankara",
     "istanbul",
     "shanghai",
@@ -658,7 +658,7 @@ def _normalize_city_or_404(name: str) -> str:
 
 def _normalize_city_list(raw: Optional[str]) -> list[str]:
     if not raw:
-        return list(DEFAULT_PREWARM_CITIES)
+        return list(DEFAULT_STATUS_CITIES)
     out: list[str] = []
     for part in str(raw).split(","):
         city = str(part or "").strip().lower().replace("-", " ")