fix: 修复竞态条件、重置逻辑、无匹配终态等关键问题

- 用 Prisma $transaction 实现 atomicUpdateRoom，防止并发写入覆盖
- 新增 POST /api/room/[id]/reset 端点，修复"再来一轮"按钮死循环
- 新增 swipeCounts 字段追踪滑动进度，检测"无人匹配"终态
- 着陆页 handleCreate 增加 res.ok 检查，防止跳转到无效房间
- 匹配或无匹配后停止轮询，减少无效请求

src/app/api/room/[id]/reset/route.ts

@@ -0,0 +1,33 @@
+import { NextResponse } from "next/server";
+import { atomicUpdateRoom } from "@/lib/store";
+
+export async function POST(
+  _req: Request,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  const { id } = await params;
+
+  try {
+    const updated = await atomicUpdateRoom(id, (data) => {
+      data.likes = {};
+      data.swipeCounts = {};
+      data.match = null;
+      return data;
+    });
+
+    if (!updated) {
+      return NextResponse.json(
+        { error: "房间不存在或已过期" },
+        { status: 404 },
+      );
+    }
+
+    return NextResponse.json({ ok: true });
+  } catch (e) {
+    console.error("Failed to reset room:", e);
+    return NextResponse.json(
+      { error: "重置失败" },
+      { status: 500 },
+    );
+  }
+}