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

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

client/lib/widgets/form_dialog.dart

@@ -1,6 +1,5 @@
-import '../core/utils/dialog_util.dart';
 import 'package:flutter/material.dart';
-import '../core/theme/app_theme.dart';
+import '../core/theme/context_tokens.dart';
 
 /// Generic dialog wrapper for forms
 class FormDialog extends StatelessWidget {
@@ -35,9 +34,9 @@ class FormDialog extends StatelessWidget {
             Container(
               height: 48,
               padding: const EdgeInsets.symmetric(horizontal: 20),
-              decoration: const BoxDecoration(
-                color: AppTheme.primary,
-                borderRadius: BorderRadius.only(
+              decoration: BoxDecoration(
+                color: context.tokens.primary,
+                borderRadius: const BorderRadius.only(
                   topLeft: Radius.circular(4),
                   topRight: Radius.circular(4),
                 ),