feat: 新增周末契约盲盒功能，首页重构为双模式入口

- 新增 BlindBoxIdea 数据模型及 migration
- 新增盲盒 API (提交想法/查询/抽取)
- 新增周末契约盲盒页面 (动效震动+彩带开奖)
- 原首页功能拆分至 /panic 路由
- 首页重构为极速救场 + 周末契约双卡片入口

src/app/api/blindbox/draw/route.ts

@@ -0,0 +1,39 @@
+import { NextRequest, NextResponse } from "next/server";
+import { prisma } from "@/lib/prisma";
+
+export async function POST(req: NextRequest) {
+  try {
+    const { roomId } = await req.json();
+
+    if (!roomId || typeof roomId !== "string") {
+      return NextResponse.json({ error: "roomId 不能为空" }, { status: 400 });
+    }
+
+    const pool = await prisma.blindBoxIdea.findMany({
+      where: { roomId: roomId.trim(), status: "in_pool" },
+      select: { id: true },
+    });
+
+    if (pool.length === 0) {
+      return NextResponse.json(
+        { error: "盒子是空的，先往里面塞点想法吧！" },
+        { status: 404 },
+      );
+    }
+
+    const picked = pool[Math.floor(Math.random() * pool.length)];
+
+    const idea = await prisma.blindBoxIdea.update({
+      where: { id: picked.id },
+      data: { status: "drawn" },
+    });
+
+    return NextResponse.json({
+      id: idea.id,
+      content: idea.content,
+      createdAt: idea.createdAt,
+    });
+  } catch {
+    return NextResponse.json({ error: "抽取失败" }, { status: 500 });
+  }
+}