feat(routing): 域名级系统锁冲突提示 + 重置默认按钮 + 客户端 follow-up 清理

承接 FT-A(GET /v1/me/routing 含只读 system_locked_domains)。

- RoutingProfile 加只读 systemLockedDomains(fromJson 读/toJson 不输出);
  routing_screen 冲突检测扩展到域名类规则(domain/domain_suffix/domain_keyword
  命中锁定域名 → systemLocked),ip_cidr 私网启发式保留。
- RoutingProfile.defaults() + RoutingProfileNotifier.resetToDefault()(复用
  _persist:乐观更新/失败回滚/存成功后自动重连,保留只读 systemLockedDomains
  不丢)+ routing_screen 加「重置默认」按钮与二次确认弹层(新增 3 个 l10n 键)。
- RoutingRule.copyWith 用哨兵支持 note 显式清空为 null;RoutingRule/Builtin/
  RoutingProfile 加值相等 operator==/hashCode。
- T8 smartRouteSub 清理:grep 全仓发现 design/prototype/i18n/alias.json →
  gen_proto_i18n.mjs(CI 漂移闸)仍有活引用,按计划口径不删,详见
  .superpowers/sdd/task-FTB-report.md。

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

client/test/unit/routing_provider_test.dart

@@ -115,6 +115,36 @@ void main() {
     expect(api.saved, hasLength(3));
   });
 
+  test('resetToDefault() 还原出厂档案,保留 systemLockedDomains,并落盘', () async {
+    final api = _FakeAccountApi()
+      ..initial = RoutingProfile.fromJson({
+        'mode': 'global',
+        'builtin': {'china_direct': false, 'lan_direct': true, 'private_via_tunnel': true},
+        'rules': [
+          {'type': 'domain', 'value': 'a.com', 'action': 'reject'},
+        ],
+        'final': 'direct',
+        'system_locked_domains': ['git.yanmeiai.com'],
+      });
+    final c = _makeContainer(api);
+    addTearDown(c.dispose);
+    await _waitLoggedIn(c);
+    await c.read(routingProfileProvider.future);
+
+    await c.read(routingProfileProvider.notifier).resetToDefault();
+
+    final state = c.read(routingProfileProvider).value!;
+    expect(state.mode, 'rule');
+    expect(state.builtin.chinaDirect, isTrue);
+    expect(state.rules, isEmpty);
+    expect(state.finalAction, 'proxy');
+    expect(state.systemLockedDomains, ['git.yanmeiai.com'],
+        reason: '只读字段随重置保留,不因重置默认档案而丢失');
+
+    expect(api.saved, hasLength(1));
+    expect(api.saved.single.mode, 'rule');
+  });
+
   test('保存失败:回退到变更前 state 且 rethrow,不静默吞', () async {
     final api = _FakeAccountApi();
     final c = _makeContainer(api);