fix: validate account status before update and update load factor hint

- Normalize non-standard status (e.g. "error") to "active" on edit load
- Add pre-submit validation for status field to prevent 400 errors
- Update load factor hint: "提高负载因子可以提高对账号的调度频率"

frontend/src/components/account/EditAccountModal.vue

@@ -1508,7 +1508,9 @@ watch(
       form.load_factor = newAccount.load_factor ?? null
       form.priority = newAccount.priority
       form.rate_multiplier = newAccount.rate_multiplier ?? 1
-      form.status = newAccount.status as 'active' | 'inactive'
+      form.status = (newAccount.status === 'active' || newAccount.status === 'inactive')
+        ? newAccount.status
+        : 'active'
       form.group_ids = newAccount.group_ids || []
       form.expires_at = newAccount.expires_at ?? null
 
@@ -2048,6 +2050,11 @@ const handleSubmit = async () => {
   if (!props.account) return
   const accountID = props.account.id
 
+  if (form.status !== 'active' && form.status !== 'inactive') {
+    appStore.showError(t('admin.accounts.pleaseSelectStatus'))
+    return
+  }
+
   const updatePayload: Record<string, unknown> = { ...form }
   try {
     // 后端期望 proxy_id: 0 表示清除代理，而不是 null