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]/route.ts

@@ -17,10 +17,17 @@ export async function GET(
       );
     }
 
+    const total = data.restaurants.length;
+    const allFinished =
+      data.users.length > 0 &&
+      data.users.every((u) => (data.swipeCounts[u] ?? 0) >= total);
+    const noMatch = allFinished && data.match === null;
+
     return NextResponse.json({
       roomId: id,
       userCount: data.users.length,
       match: data.match,
+      noMatch,
       restaurants: data.restaurants,
     });
   } catch (e) {