refactor(client): widgets 颜色迁移到 context.tokens

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/lib/widgets/page_scaffold.dart

@@ -1,5 +1,5 @@
 import 'package:flutter/material.dart';
-import '../core/theme/app_theme.dart';
+import '../core/theme/context_tokens.dart';
 
 class PageScaffold extends StatefulWidget {
   final String title;
@@ -54,14 +54,14 @@ class _PageScaffoldState extends State<PageScaffold>
       crossAxisAlignment: CrossAxisAlignment.start,
       children: [
         Container(
-          color: AppTheme.surface,
+          color: context.tokens.surface,
           child: TabBar(
             controller: _controller,
             isScrollable: true,
             tabAlignment: TabAlignment.start,
-            labelColor: AppTheme.primary,
-            unselectedLabelColor: AppTheme.textSecondary,
-            indicatorColor: AppTheme.primary,
+            labelColor: context.tokens.primary,
+            unselectedLabelColor: context.tokens.muted,
+            indicatorColor: context.tokens.primary,
             indicatorWeight: 2,
             labelStyle:
                 const TextStyle(fontSize: 14, fontWeight: FontWeight.w500),