전역 구조 리팩터링 및 테스트 확장

lib/widgets/components/page_header.dart

@@ -25,10 +25,7 @@ class PageHeader extends StatelessWidget {
     return Row(
       crossAxisAlignment: CrossAxisAlignment.start,
       children: [
-        if (leading != null) ...[
-          leading!,
-          const SizedBox(width: 16),
-        ],
+        if (leading != null) ...[leading!, const SizedBox(width: 16)],
         Expanded(
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
@@ -42,16 +39,9 @@ class PageHeader extends StatelessWidget {
           ),
         ),
         if (actions != null && actions!.isNotEmpty) ...[
-          Wrap(
-            spacing: 12,
-            runSpacing: 12,
-            children: actions!,
-          ),
-        ],
-        if (trailing != null) ...[
-          const SizedBox(width: 16),
-          trailing!,
+          Wrap(spacing: 12, runSpacing: 12, children: actions!),
         ],
+        if (trailing != null) ...[const SizedBox(width: 16), trailing!],
       ],
     );
   }