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/core.py

@@ -21,7 +21,6 @@ from src.data_collection.country_networks import provider_coverage_summary
 from src.data_collection.city_risk_profiles import CITY_RISK_PROFILES  # noqa: F401
 from src.data_collection.polymarket_readonly import PolymarketReadOnlyLayer
 from src.auth.supabase_entitlement import SUPABASE_ENTITLEMENT, extract_bearer_token
-from src.utils.prewarm_dashboard import get_prewarm_runtime_summary
 from src.utils.metrics import (
     build_metrics_summary,
     counter_inc,
@@ -836,6 +835,5 @@ def build_system_status_payload() -> Dict[str, Any]:
         "probability": _probability_summary(),
         "training_data": _training_data_summary(),
         "station_networks": provider_coverage_summary(),
-        "prewarm": get_prewarm_runtime_summary(),
         "cities_count": len(CITIES),
     }