feat(i18n): 完成全量 UI 文本国际化，替换所有硬编码中文为 AppLocalizations 调用

- core/localization: 新增约 60 个翻译键（含参数化方法），中英双语覆盖
- shared/widgets: CommonDialog 默认参数国际化
- features/home: 完成页操作步骤指引、状态栏串口连接状态、程序列表状态标签
- features/programs: 表头状态列、表单验证提示、导入/模板操作反馈、删除确认（参数化）
- features/program_detail: 步骤列表/表单标题、删除确认、速度档位显示（参数化）
- features/device: run_state_provider 错误消息改为错误码
- features/settings: 升级页、密码面板、语言面板、U盘导入面板、串口配置面板全部替换

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

lib/features/program_detail/pages/program_detail_page.dart

@@ -107,7 +107,7 @@ class _ProgramDetailPageState extends ConsumerState<ProgramDetailPage> {
                                     if (success) {
                                       ScaffoldMessenger.of(context).showSnackBar(
                                         SnackBar(
-                                          content: Text('步骤已更新'),
+                                          content: Text(l10n?.stepUpdated ?? '步骤已更新'),
                                           backgroundColor: AppTheme.successColor,
                                         ),
                                       );
@@ -125,7 +125,7 @@ class _ProgramDetailPageState extends ConsumerState<ProgramDetailPage> {
                                       ),
                                       const SizedBox(height: 16),
                                       Text(
-                                        '请选择或添加步骤',
+                                        l10n?.selectStepFirst ?? '请选择或添加步骤',
                                         style: TextStyle(
                                           color: AppTheme.textSecondary,
                                           fontSize: 16,
@@ -164,7 +164,7 @@ class _ProgramDetailPageState extends ConsumerState<ProgramDetailPage> {
         children: [
           IconButton(
             icon: const Icon(Icons.arrow_back),
-            tooltip: l10n?.backToHome ?? '返回',
+            tooltip: l10n?.back ?? '返回',
             onPressed: () => context.go('/?tab=1'),
           ),
           const SizedBox(width: 8),
@@ -184,7 +184,7 @@ class _ProgramDetailPageState extends ConsumerState<ProgramDetailPage> {
             onPressed: () {
               ScaffoldMessenger.of(context).showSnackBar(
                 SnackBar(
-                  content: Text('已保存'),
+                  content: Text(l10n?.saved ?? '已保存'),
                   backgroundColor: AppTheme.successColor,
                 ),
               );