SSE Patch 增量推送架构全链路实现

- web/sse_manager.py: asyncio.Queue 连接池 + broadcast + event_stream
- web/routers/sse_router.py: GET /api/events + POST /api/internal/collector-patch
- weather_sources.py: 采集后 POST patch 给 web
- Nginx polyweather.conf: /api/events proxy_buffering off
- frontend/api/events/route.ts: Next.js SSE 代理
- frontend/hooks/use-sse-patches.ts: EventSource + useLatestPatch + 重连
- LiveTemperatureThresholdChart: mergePatchIntoHourly 增量合并
- scan-terminal-query: 接入 SSE patch 更新行数据
- 新增 ssePatchArchitecture.test.ts 架构测试

frontend/app/api/events/route.ts

@@ -0,0 +1,40 @@
+import { NextRequest, NextResponse } from "next/server";
+
+const API_BASE = process.env.POLYWEATHER_API_BASE_URL;
+
+export const dynamic = "force-dynamic";
+export const runtime = "nodejs";
+
+export async function GET(req: NextRequest) {
+  if (!API_BASE) {
+    return NextResponse.json(
+      { error: "POLYWEATHER_API_BASE_URL is not configured" },
+      { status: 500 },
+    );
+  }
+
+  const upstream = await fetch(`${API_BASE.replace(/\/+$/, "")}/api/events`, {
+    cache: "no-store",
+    headers: {
+      Accept: "text/event-stream",
+      Cookie: req.headers.get("cookie") || "",
+    },
+  });
+
+  if (!upstream.ok || !upstream.body) {
+    return NextResponse.json(
+      { error: `SSE upstream failed with HTTP ${upstream.status}` },
+      { status: upstream.status || 502 },
+    );
+  }
+
+  return new Response(upstream.body, {
+    status: 200,
+    headers: {
+      "Content-Type": "text/event-stream",
+      "Cache-Control": "no-cache, no-transform",
+      Connection: "keep-alive",
+      "X-Accel-Buffering": "no",
+    },
+  });
+}