perf: 优化会员卡购买页面

packages/app/src/stores/user.ts

@@ -88,12 +88,14 @@ export const useUserStore = defineStore('user', () => {
     }
   }
 
-  async function fetchMemberships() {
-    if (!isLoggedIn()) return
+  async function fetchMemberships(): Promise<boolean> {
+    if (!isLoggedIn()) return false
     try {
       memberships.value = await get<MembershipWithCardType[]>('/membership/my')
+      return true
     } catch (err) {
       console.error('Fetch memberships failed:', err)
+      return false
     }
   }