fix(stickman): 使用顶部对齐实现昵称与数量标签的中心对齐

昵称标签和数量标签高度相同，顶部对齐即可实现水平中心对齐

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

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

frontend/mobile-app/lib/features/authorization/presentation/widgets/stickman_race_widget.dart

@@ -256,12 +256,10 @@ class _StickmanRaceWidgetState extends State<StickmanRaceWidget>
           top: verticalPosition - bounce,
           child: Row(
             mainAxisSize: MainAxisSize.min,
-            crossAxisAlignment: CrossAxisAlignment.end, // 底部对齐
+            crossAxisAlignment: CrossAxisAlignment.start, // 顶部对齐，昵称和数量标签高度相同，自然中心对齐
             children: [
-              // 昵称标签 - 固定在左边，与数量标签底部对齐
-              Padding(
-                padding: const EdgeInsets.only(bottom: 38), // 火柴人高度36 + 间距2
-                child: SizedBox(
+              // 昵称标签 - 与数量标签顶部对齐（两者高度相近，实现中心对齐）
+              SizedBox(
                 width: nicknameAreaWidth,
                 child: Container(
                   padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 2),
@@ -290,7 +288,6 @@ class _StickmanRaceWidgetState extends State<StickmanRaceWidget>
                   ),
                 ),
               ),
-              ),
               // 火柴人和数量标签
               SizedBox(
                 width: stickmanBoxWidth.clamp(60.0, double.infinity),