fix: 购物车页面未登录时不调用需要认证的API

- fetchAddresses 未登录时跳过
- fetchUserProfile 未登录时跳过（已有）
- 避免触发 401 跳转登录页

frontend/src/views/user/Cart.vue

@@ -482,6 +482,10 @@ async function fetchPaymentChannels() {
 }
 
 async function fetchAddresses() {
+  // 未登录时静默跳过
+  const token = localStorage.getItem('token')
+  if (!token) return
+  
   try {
     const res: any = await addressApi.list()
     addresses.value = res.data || []