修复温度曲线图 DEB 路径不显示：后端 v2 API 的 timeseries.hourly 映射到前端 CityDetail.hourly

- normalizeCityDetailPayload 新增 timeseries.hourly → hourly 字段提升
- 预热列表 DEFAULT_CITIES 扩展到 33 城，覆盖全部机场推送城市

frontend/app/api/city/[name]/route.ts

@@ -109,6 +109,12 @@ function buildFallbackCityDetail(name: string, depth: string, summary: Record<st
 function normalizeCityDetailPayload(data: unknown) {
   if (!data || typeof data !== "object") return data;
   const payload = data as Record<string, any>;
+
+  // Backend v2 nests hourly under timeseries; chart expects it at top level.
+  if (!payload.hourly && payload.timeseries?.hourly) {
+    payload.hourly = payload.timeseries.hourly;
+  }
+
   if (!payload.market_scan && payload.market_scan_payload) {
     return {
       ...payload,