feat: Implement initial PolyWeather dashboard with city list, detail view, map, and API endpoints.

frontend/lib/api.ts

@@ -1,9 +1,20 @@
 import type { CityDetail, CitySummary } from "@/lib/types";
 
+async function readError(res: Response, fallback: string) {
+  try {
+    const data = await res.json();
+    const msg = data?.error ? String(data.error) : fallback;
+    const detail = data?.detail ? ` ${String(data.detail)}` : "";
+    return `${msg}${detail}`.trim();
+  } catch {
+    return `${fallback}: ${res.status}`;
+  }
+}
+
 export async function getCities(): Promise<CitySummary[]> {
   const res = await fetch("/api/cities", { cache: "no-store" });
   if (!res.ok) {
-    throw new Error(`Failed to load cities: ${res.status}`);
+    throw new Error(await readError(res, `Failed to load cities (${res.status})`));
   }
   const data = await res.json();
   return data.cities ?? [];
@@ -21,7 +32,9 @@ export async function getCityDetail(
     },
   );
   if (!res.ok) {
-    throw new Error(`Failed to load city detail: ${res.status}`);
+    throw new Error(
+      await readError(res, `Failed to load city detail (${res.status})`),
+    );
   }
   return await res.json();
 }

frontend/lib/i18n.ts

@@ -0,0 +1,55 @@
+export type Locale = "zh" | "en";
+
+export const copy = {
+  en: {
+    brandSubtitle: "Global Weather Risk Intelligence",
+    technicalGuide: "Technical Guide",
+    monitoredCities: "Monitored Cities",
+    cityDetail: "City Detail",
+    selectCityHint: "Select a city from the left list or map marker.",
+    live: "Live",
+    cities: "Cities",
+    currentMax: "Current / Max",
+    cloud: "Cloud",
+    wind: "Wind",
+    topProb: "Top Settlement Probabilities",
+    noProb: "No probability data yet.",
+    aiSummary: "AI Summary",
+    noAnalysis: "No analysis yet.",
+    refresh: "Refresh",
+    fahrenheit: "Fahrenheit",
+    celsius: "Celsius",
+    high: "High",
+    medium: "Med",
+    low: "Low",
+    loadCitiesFailed: "Failed to load cities",
+    loadCityDetailFailed: "Failed to load city detail",
+    backendConfigMissing:
+      "Server config missing: POLYWEATHER_API_BASE_URL is not set.",
+  },
+  zh: {
+    brandSubtitle: "全球天气风险智能分析",
+    technicalGuide: "技术说明",
+    monitoredCities: "监控城市",
+    cityDetail: "城市详情",
+    selectCityHint: "请从左侧列表或地图标记选择城市。",
+    live: "实时",
+    cities: "城市",
+    currentMax: "当前 / 最高",
+    cloud: "云量",
+    wind: "风速",
+    topProb: "结算概率Top3",
+    noProb: "暂无概率数据",
+    aiSummary: "AI 分析",
+    noAnalysis: "暂无分析",
+    refresh: "刷新",
+    fahrenheit: "华氏",
+    celsius: "摄氏",
+    high: "高",
+    medium: "中",
+    low: "低",
+    loadCitiesFailed: "城市列表加载失败",
+    loadCityDetailFailed: "城市详情加载失败",
+    backendConfigMissing: "服务端未配置 POLYWEATHER_API_BASE_URL。",
+  },
+} as const;