feat(app): 完善播放协议搜索与空状态

lib/core/widgets/empty_state.dart

@@ -115,7 +115,6 @@ class _EmptyCopy extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final scheme = Theme.of(context).colorScheme;
     return Column(
       mainAxisSize: MainAxisSize.min,
       children: [
@@ -126,10 +125,10 @@ class _EmptyCopy extends StatelessWidget {
             maxLines: 2,
             overflow: TextOverflow.ellipsis,
             textAlign: TextAlign.center,
-            style: TextStyle(
-              color: scheme.onSurface,
+            style: const TextStyle(
+              color: AppColors.textTertiary,
               fontSize: 15,
-              fontWeight: FontWeight.w600,
+              fontWeight: FontWeight.w400,
               height: 1.35,
             ),
           ),