fix(auth): 登录成功时将familyId持久化到userInfo缓存，避免页面误判无家庭而重复创建

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

cfc-frontend/App.vue

@@ -119,9 +119,11 @@ export default {
       if (data.openid) {
         uni.setStorageSync('openid', data.openid)
       }
+      // familyId 必须持久化：家庭在注册时已由后端创建，缺失会导致页面误判无家庭而重复创建
       uni.setStorageSync('userInfo', {
         nickname: data.nickname,
-        userId: data.userId
+        userId: data.userId,
+        familyId: data.familyId
       })
       this.$store.commit('setToken', data.token)
       // 同步 familyId 到 store（hasFamily getter 依赖；auto-login 路径）

cfc-frontend/pages/login/login.vue

@@ -147,7 +147,8 @@ export default {
       uni.setStorageSync('isSwitchedChild', false)
       uni.setStorageSync('isSwitchedTeacher', false)
       if (data.openid) uni.setStorageSync('openid', data.openid)
-      uni.setStorageSync('userInfo', { nickname: data.nickname, userId: data.userId })
+      // familyId 必须持久化：家庭在注册时已由后端创建，缺失会导致页面误判无家庭而重复创建
+      uni.setStorageSync('userInfo', { nickname: data.nickname, userId: data.userId, familyId: data.familyId })
       if (data.phone) uni.setStorageSync('phone', data.phone)
       if (data.teacherStatus) uni.setStorageSync('teacherStatus', data.teacherStatus)
       if (data.teacherRejectReason) uni.setStorageSync('teacherRejectReason', data.teacherRejectReason)