feat: 盲盒房间体系重构 — 强制登录、独立房间、用户归属

- 新增 BlindBoxRoom/BlindBoxMember 模型，BlindBoxIdea 增加 userId/drawnById
- 新增房间 API（创建/加入/列表/详情），所有盲盒 API 增加认证和成员校验
- 新建盲盒大厅页面（三层引导式设计：未登录氛围页/首次创建引导/房间列表）
- 新建盲盒房间页面（成员校验/邀请分享/用户归属展示/自动聚焦）
- 首页删除契约画廊和 localStorage 盲盒逻辑，周末契约跳转到 /blindbox
- 清理旧路由 /room/[id]/blindbox
- 提取共享工具 src/lib/blindbox.ts（错误响应/房间号生成/成员校验）
- AuthModal 支持 defaultTab 参数
- 更新项目规范：新项目原则、代码优雅和复用优先

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

@@ -0,0 +1,69 @@
+import { NextRequest, NextResponse } from "next/server";
+import { prisma } from "@/lib/prisma";
+import { errorResponse } from "@/lib/blindbox";
+
+export async function GET(req: NextRequest) {
+  const userId = req.nextUrl.searchParams.get("userId");
+
+  if (!userId) {
+    return errorResponse("请先登录", 401);
+  }
+
+  try {
+    const memberships = await prisma.blindBoxMember.findMany({
+      where: { userId },
+      include: {
+        room: {
+          include: {
+            members: {
+              include: { user: { select: { id: true, username: true, avatar: true } } },
+              orderBy: { joinedAt: "asc" },
+              take: 5,
+            },
+            _count: {
+              select: {
+                ideas: true,
+                members: true,
+              },
+            },
+            ideas: {
+              where: { status: "drawn" },
+              orderBy: { createdAt: "desc" },
+              take: 1,
+              select: { content: true, createdAt: true },
+            },
+          },
+        },
+      },
+      orderBy: { joinedAt: "desc" },
+    });
+
+    const rooms = memberships.map((m) => ({
+      id: m.room.id,
+      code: m.room.code,
+      name: m.room.name,
+      memberCount: m.room._count.members,
+      ideaCount: m.room._count.ideas,
+      poolCount: 0,
+      members: m.room.members.map((mb) => mb.user),
+      lastDrawn: m.room.ideas[0] ?? null,
+      joinedAt: m.joinedAt,
+    }));
+
+    const roomIds = rooms.map((r) => r.id);
+    const poolCounts = await prisma.blindBoxIdea.groupBy({
+      by: ["roomId"],
+      where: { roomId: { in: roomIds }, status: "in_pool" },
+      _count: true,
+    });
+    const poolMap = new Map(poolCounts.map((p) => [p.roomId, p._count]));
+
+    for (const room of rooms) {
+      room.poolCount = poolMap.get(room.id) ?? 0;
+    }
+
+    return NextResponse.json({ rooms });
+  } catch {
+    return errorResponse("获取房间列表失败", 500);
+  }
+}