fix: 修复恢复账号页面键盘弹出时的溢出错误

- 将 Column 改为 SingleChildScrollView 包裹，支持滚动
- 在底部添加额外间距，避免内容被键盘遮挡
- 修复 RenderFlex overflowed by 18 pixels 错误

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/mobile-app/lib/features/auth/presentation/pages/phone_login_page.dart

@@ -149,7 +149,7 @@ class _PhoneLoginPageState extends ConsumerState<PhoneLoginPage> {
       body: GestureDetector(
         onTap: () => FocusScope.of(context).unfocus(),
         child: SafeArea(
-          child: Padding(
+          child: SingleChildScrollView(
             padding: EdgeInsets.symmetric(horizontal: 24.w),
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
@@ -192,6 +192,7 @@ class _PhoneLoginPageState extends ConsumerState<PhoneLoginPage> {
                 SizedBox(height: 24.h),
                 // 注册提示
                 _buildRegisterHint(),
+                SizedBox(height: 32.h),
               ],
             ),
           ),