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

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

@@ -1,12 +1,18 @@
 import { NextRequest, NextResponse } from "next/server";
 
-const API_BASE =
-  process.env.POLYWEATHER_API_BASE_URL || "http://127.0.0.1:8000";
+const API_BASE = process.env.POLYWEATHER_API_BASE_URL;
 
 export async function GET(
   req: NextRequest,
   context: { params: Promise<{ name: string }> },
 ) {
+  if (!API_BASE) {
+    return NextResponse.json(
+      { error: "POLYWEATHER_API_BASE_URL is not configured" },
+      { status: 500 },
+    );
+  }
+
   const { name } = await context.params;
   const forceRefresh = req.nextUrl.searchParams.get("force_refresh") ?? "false";
   const url = `${API_BASE}/api/city/${encodeURIComponent(name)}?force_refresh=${forceRefresh}`;
@@ -17,8 +23,9 @@ export async function GET(
       cache: "no-store",
     });
     if (!res.ok) {
+      const raw = await res.text();
       return NextResponse.json(
-        { error: `Backend returned ${res.status}` },
+        { error: `Backend returned ${res.status}`, detail: raw.slice(0, 300) },
         { status: 502 },
       );
     }