Use static terminal update announcements

frontend/app/api/system/update-announcement/route.ts

@@ -1,30 +0,0 @@
-import { NextResponse } from "next/server";
-import { buildProxyExceptionResponse } from "@/lib/api-proxy";
-
-const API_BASE = process.env.POLYWEATHER_API_BASE_URL;
-const BACKEND = API_BASE ? `${API_BASE}/api/system/update-announcement` : "";
-
-export async function GET() {
-  if (!API_BASE) {
-    return NextResponse.json(
-      { error: "POLYWEATHER_API_BASE_URL is not configured" },
-      { status: 500 },
-    );
-  }
-
-  try {
-    const res = await fetch(BACKEND, { cache: "no-store" });
-    const raw = await res.text();
-    return new NextResponse(raw, {
-      status: res.status,
-      headers: {
-        "Cache-Control": "no-store",
-        "Content-Type": "application/json",
-      },
-    });
-  } catch (error) {
-    return buildProxyExceptionResponse(error, {
-      publicMessage: "Failed to fetch update announcement",
-    });
-  }
-}