feat(sub): opt-in dns and sniffer from remote Clash rules (#6868)

Public Mihomo templates ship rules, rule-providers and proxy-groups together
with a dns block those rules depend on (fake-ip ranges, nameserver policy).
Pasting a template inline keeps its dns, but pointing the global routing rules
at its URL dropped it, so URL users had to give up auto-refresh to keep it.

A new switch, subClashRemoteDNS (off by default), also takes the remote dns and
sniffer maps. It is opt-in because a remote dns block decides where clients send
every lookup. A malformed dns or sniffer value is skipped, not the whole template.
The component-test teardown now outlasts AntD Form's 10ms error debounce, which
otherwise fired after jsdom was gone.

frontend/src/test/setup.components.ts

@@ -95,6 +95,12 @@ afterEach(async () => {
   for (let i = 0; i < 3; i += 1) {
     await new Promise((resolve) => setTimeout(resolve, 0));
   }
+  /*
+   * AntD Form debounces clearing its error list by 10ms (useDebounce via
+   * rc-util useDelayState), and that timer survives unmount. Wait past it so
+   * it fires while `window` still exists.
+   */
+  await new Promise((resolve) => setTimeout(resolve, 20));
 });
 
 import { HttpUtil, Msg } from '@/utils';

frontend/src/test/subscription-general-tab.test.tsx

@@ -167,6 +167,29 @@ describe('SubscriptionGeneralTab', () => {
     },
   );
 
+  it.each([false, true])(
+    'updates the Clash remote DNS opt-in, not the routing switch, when stored as %s',
+    (enabled) => {
+      const updateSetting = vi.fn();
+
+      renderWithProviders(
+        <MemoryRouter initialEntries={['/settings#subscription']}>
+          <SubscriptionGeneralTab
+            allSetting={new AllSetting({ subClashEnableRouting: true, subClashRemoteDNS: enabled })}
+            updateSetting={updateSetting}
+          />
+        </MemoryRouter>,
+      );
+
+      fireEvent.click(screen.getByRole('tab', { name: /Clash/ }));
+      const remoteDNSSwitch = screen.getByRole('switch', { name: 'Use DNS from remote rules' });
+      expect(remoteDNSSwitch.getAttribute('aria-checked')).toBe(String(enabled));
+      fireEvent.click(remoteDNSSwitch);
+
+      expect(updateSetting).toHaveBeenCalledExactlyOnceWith({ subClashRemoteDNS: !enabled });
+    },
+  );
+
   it('shows the Happ link gate from the QR settings deep link without enabling generation', () => {
     const updateSetting = vi.fn();