fix: 修复验证码输入框数字显示不全

- 增加输入框尺寸 48x56 -> 50x60
- 增大字体 20sp -> 24sp
- 移除 height: 1.2 行高限制

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

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

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

@@ -366,8 +366,8 @@ class _SmsVerifyPageState extends ConsumerState<SmsVerifyPage> {
       mainAxisAlignment: MainAxisAlignment.spaceBetween,
       children: List.generate(6, (index) {
         return SizedBox(
-          width: 48.w,
-          height: 56.h,
+          width: 50.w,
+          height: 60.h,
           child: KeyboardListener(
             focusNode: FocusNode(),
             onKeyEvent: (event) => _onKeyEvent(index, event),
@@ -404,10 +404,9 @@ class _SmsVerifyPageState extends ConsumerState<SmsVerifyPage> {
                 ),
               ),
               style: TextStyle(
-                fontSize: 20.sp,
+                fontSize: 24.sp,
                 fontWeight: FontWeight.w700,
                 color: const Color(0xFF333333),
-                height: 1.2,
               ),
               onChanged: (value) => _onCodeChanged(index, value),
             ),