feat(admin): open controller-link settings entries from the settings index

A settings entry with a controller opens that controller's route from
its card (settingsPath); singleton cards still open /settings/<code>.
On a linked controller with no navigation entry of its own the rail
marks Settings current, the breadcrumbs read Settings > entry label
(plus the record title on record and create routes) and the page title
uses the entry label. The settings docs describe the admin behaviour;
the embedded admin shell is rebuilt.

admin/tests/app/pageTitle.test.ts

@@ -33,6 +33,17 @@ describe('documentTitleForRoute', () => {
     expect(documentTitleForRoute((await routerAt('/settings/mail')).currentRoute.value)).toBe('Mail | SummerCMS')
   })
 
+  it('uses the settings entry label on a settings-linked controller', async () => {
+    await signIn()
+    setNavigation(navigationFixture.data)
+    const locales = { ...settingsFixture.list.data[0]!, code: 'locales', label: 'Locales', model: '', controller: 'acme.lang.locales' }
+    setSettings([...settingsFixture.list.data, locales])
+    expect(documentTitleForRoute((await routerAt('/acme/lang/locales')).currentRoute.value)).toBe('Locales | SummerCMS')
+    expect(documentTitleForRoute((await routerAt('/acme/lang/locales/3')).currentRoute.value)).toBe('Locales | SummerCMS')
+    setRecordCrumb('Polish')
+    expect(documentTitleForRoute((await routerAt('/acme/lang/locales/3')).currentRoute.value)).toBe('Polish | SummerCMS')
+  })
+
   it('uses translated indicators for login, the empty home and not found', async () => {
     expect(documentTitleForRoute((await routerAt('/login')).currentRoute.value)).toBe('Witaj ponownie | SummerCMS')
     await signIn()