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/settings/widgets/language_panel.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../../core/localization/app_localizations.dart';
 import '../../../core/localization/locale_provider.dart';
 import '../../../core/theme/app_theme.dart';
 
@@ -13,6 +14,7 @@ class LanguagePanel extends ConsumerWidget {
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
+    final l10n = AppLocalizations.of(context);
     final locale = ref.watch(localeProvider);
     final currentLang = locale.languageCode;
 
@@ -20,7 +22,7 @@ class LanguagePanel extends ConsumerWidget {
       padding: EdgeInsets.zero,
       children: [
         _SectionCard(
-          title: '语言设置',
+          title: l10n?.languageSettings ?? '语言设置',
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.stretch,
             children: [
@@ -46,7 +48,7 @@ class LanguagePanel extends ConsumerWidget {
         Padding(
           padding: const EdgeInsets.symmetric(horizontal: 4),
           child: Text(
-            '切换语言后立即生效',
+            l10n?.switchLanguageEffect ?? '切换语言后立即生效',
             style: TextStyle(color: AppTheme.textSecondary, fontSize: 12),
           ),
         ),