refactor: 提取 requireUserId/requireUser/requireMembership 校验工具

- 新增 requireUserId：统一 14 处 userId 非空校验，返回 401
- 新增 requireUser：统一 4 处用户存在性检查，返回 404
- validateMembership 升级为 requireMembership，直接抛 403
- 混合校验拆分为 auth(401) + 字段(400)，状态码更准确

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

@@ -1,10 +1,9 @@
 import { NextResponse } from "next/server";
 import { prisma } from "@/lib/prisma";
-import { apiHandler, ApiError } from "@/lib/api";
+import { apiHandler, requireUserId } from "@/lib/api";
 
 export const GET = apiHandler(async (req) => {
-  const userId = req.nextUrl.searchParams.get("userId");
-  if (!userId) throw new ApiError("请先登录", 401);
+  const userId = requireUserId(req.nextUrl.searchParams.get("userId"));
 
   const memberships = await prisma.blindBoxMember.findMany({
     where: { userId },