feat(mine): 我的 Tab 全量实现 (#5~#13)

从 im-client-ios-swift-demo 搬运 Settings 逻辑，对齐 Gitea issue #5–#13

## 基础设施
- AuthNotifier 新增 currentUid 字段，login() 接受 uid 参数 (#5)
- LoginViewModel 登录成功后传入 user.uid
- ApiPaths 补充 account/block/store 系列路径
- Tab 重命名"设置"→"我的"，icon 改为 person_outline (#5)
- AppRouteName 新增5条子路由 (edit-profile/blocklist/language/network-diagnostics/about)
- app_router + auth_guard 同步注册新路由

## Settings Feature
- SettingsViewModel 重写为 NotifierProvider（去除 @riverpod 依赖）
  - build() 自动触发 loadProfile()
  - logout() 完整流程：API → WS 断开 → DB 关闭 → AuthNotifier
  - 6 个 navigateTo* 方法
- SettingsPage 完整 UI：资料卡 / 偏好设置 / 工具 / 关于 / 退出登录按钮 (#5 #7)
- FetchProfileUseCase: GET /app/api/user/profile (#5)
- LogoutUseCase: logout + disconnect + closeDatabase (#7)
- UpdateProfileUseCase + UpdateProfileRequest: POST /app/api/user/update-profile (#6)
- EditProfilePage + EditProfileViewModel: 昵称/bio 编辑 (#6)
- LanguagePage: 语言选择 UI 框架，l10n_sdk 待接入 (#9)
- BlocklistPage: 黑名单框架，API 待实现 (#10)
- NetworkDiagnosticsPage + ViewModel: 四步诊断（连通/TCP/DNS/HTTPS）(#12)
- AboutPage: 版本号 + 服务条款/隐私政策入口 (#13)
- settings_providers.dart: 扩展 DI 装配

## 文档
- Doc/mine_tab_architecture.md: 架构说明、数据流、路由、待完成事项

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/im_app/lib/features/settings/view/language_page.dart

@@ -0,0 +1,64 @@
+import 'package:flutter/material.dart';
+
+/// 语言设置页
+///
+/// 对应 Gitea issue #9
+/// TODO: 接入 l10n_sdk，实现语言切换持久化
+class LanguagePage extends StatefulWidget {
+  const LanguagePage({super.key});
+
+  @override
+  State<LanguagePage> createState() => _LanguagePageState();
+}
+
+class _LanguagePageState extends State<LanguagePage> {
+  /// TODO: 从 l10n_sdk / Locale 读取当前语言
+  String _selected = 'zh';
+
+  static const _languages = [
+    _LangOption(code: 'zh', label: '简体中文', nativeLabel: '简体中文'),
+    _LangOption(code: 'en', label: '英文', nativeLabel: 'English'),
+    _LangOption(code: 'zh-TW', label: '繁体中文', nativeLabel: '繁體中文'),
+  ];
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('语言')),
+      body: ListView.separated(
+        itemCount: _languages.length,
+        separatorBuilder: (_, __) => const Divider(height: 1, indent: 16),
+        itemBuilder: (context, index) {
+          final lang = _languages[index];
+          final isSelected = _selected == lang.code;
+          return ListTile(
+            title: Text(lang.nativeLabel),
+            subtitle: lang.label != lang.nativeLabel ? Text(lang.label) : null,
+            trailing: isSelected
+                ? Icon(Icons.check, color: Theme.of(context).colorScheme.primary)
+                : null,
+            onTap: () {
+              setState(() => _selected = lang.code);
+              // TODO: ref.read(localeProvider.notifier).setLocale(lang.code)
+              ScaffoldMessenger.of(context).showSnackBar(
+                SnackBar(content: Text('语言已切换为 ${lang.nativeLabel}（持久化待接入）')),
+              );
+            },
+          );
+        },
+      ),
+    );
+  }
+}
+
+class _LangOption {
+  const _LangOption({
+    required this.code,
+    required this.label,
+    required this.nativeLabel,
+  });
+
+  final String code;
+  final String label;
+  final String nativeLabel;
+}