refactor(mobile-app): 简化删除账号确认对话框文案

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mobile-app/lib/features/account/presentation/pages/account_switch_page.dart

@@ -126,11 +126,7 @@ class _AccountSwitchPageState extends ConsumerState<AccountSwitchPage> {
       context: context,
       builder: (context) => AlertDialog(
         title: const Text('删除账号'),
-        content: Text(
-          '确定要删除账号 "${account.username}" 吗？\n\n'
-          '删除后该账号的所有本地数据将被清除，'
-          '如需恢复请使用助记词重新导入。',
-        ),
+        content: Text('确定要删除账号 "${account.username}" 吗？'),
         actions: [
           TextButton(
             onPressed: () => Navigator.of(context).pop(false),