fix: login persistence, username login, realtime refresh, group name uniqueness

- Fix cookie path to '/' for auth persistence across page refreshes
- Login field now accepts both username and email
- Add 30s polling for group list and team session status refresh
- Add group name uniqueness check before creation

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/views/Layout.vue

@@ -23,16 +23,28 @@ const showScheduleModal = ref(false)
 const showCreateGroup = ref(false)
 const showJoinGroup = ref(false)
 
+let refreshTimer: ReturnType<typeof setInterval> | null = null
+
 onMounted(async () => {
   await userStore.initUser()
   await groupStore.loadGroups()
   await teamStore.loadActiveSession()
   await notificationStore.loadPendingInvitations()
   await notificationStore.startListening()
+
+  // 每30秒轮询刷新群组列表和临时小组状态
+  refreshTimer = setInterval(async () => {
+    await groupStore.loadGroups()
+    await teamStore.loadActiveSession()
+  }, 30000)
 })
 
 onUnmounted(() => {
   notificationStore.stopListening()
+  if (refreshTimer) {
+    clearInterval(refreshTimer)
+    refreshTimer = null
+  }
 })
 
 function handleLogout() {

frontend/src/views/Login.vue

@@ -9,19 +9,19 @@ import PasswordInput from '@/components/common/PasswordInput.vue'
 const router = useRouter()
 const userStore = useUserStore()
 
-const email = ref('')
+const identity = ref('')
 const password = ref('')
 const loading = ref(false)
 
 async function handleLogin() {
-  if (!email.value || !password.value) {
-    ElMessage.warning('请输入邮箱和密码')
+  if (!identity.value || !password.value) {
+    ElMessage.warning('请输入用户名/邮箱和密码')
     return
   }
 
   try {
     loading.value = true
-    await userStore.login(email.value, password.value)
+    await userStore.login(identity.value, password.value)
 
     const redirect = '/'
     router.push(redirect)
@@ -45,12 +45,11 @@ async function handleLogin() {
 
       <form class="login-form" @submit.prevent="handleLogin">
         <div class="form-group">
-          <label for="email">邮箱</label>
+          <label for="identity">用户名 / 邮箱</label>
           <el-input
-            id="email"
-            v-model="email"
-            type="email"
-            placeholder="请输入邮箱"
+            id="identity"
+            v-model="identity"
+            placeholder="请输入用户名或邮箱"
             required
           />
         </div>