fix(后台本地预览): 补上会员档位 mock 接口

- scripts/admin-web-fake-api.mjs：新增 /admin/api/profile/membership-plans 的 GET 列表与 POST 回显，避免页面 response.entries 为 undefined

Co-authored-by: Junie <junie@jetbrains.com>

scripts/admin-web-fake-api.mjs

@@ -736,6 +736,38 @@ function route(pathname, method, url) {
       scannedCount: orders.length,
     };
   }
+  if (pathname === '/admin/api/profile/membership-plans') {
+    const plan = (
+      planId,
+      title,
+      rank,
+      monthPriceCents,
+      yearPriceCents,
+      periodPoints,
+      modelAccess,
+      concurrentJobLimit,
+      enabled,
+    ) => ({
+      plan: planId,
+      title,
+      rank,
+      monthPriceCents,
+      yearPriceCents,
+      periodPoints,
+      modelAccess,
+      concurrentJobLimit,
+      enabled,
+    });
+    const plans = [
+      plan('normal', '非会员', 0, 0, 0, 0, 'basic', 1, false),
+      plan('starter', '入门会员', 1, 3_900, 39_000, 400, 'basic', 1, true),
+      plan('plus', '轻享会员', 2, 9_900, 99_000, 1_150, 'full', 3, true),
+      plan('pro', '专业会员', 3, 29_900, 299_000, 3_650, 'full', 5, true),
+      plan('max', '旗舰会员', 4, 69_900, 699_000, 8_650, 'full', 128, true),
+    ];
+    // 本地预览不解析请求体：POST 统一回显 starter，仅用于页面回填。
+    return method === 'POST' ? plans[1] : { entries: plans };
+  }
   if (pathname === '/admin/api/profile/recharge-products') {
     const product = (
       productId,