fix(front): settings skeleton, app-detail header & empty favorites (#21209)

Three small post-redesign UI fixes. Each is an independent commit, so
they can be split into separate PRs if preferred.

## 1. Settings loading skeleton — match the rounded-card layout

The redesign (#21131) moved settings chrome into a rounded card
(`SettingsPageLayout`: bordered header with breadcrumb + centered title,
optional secondary bar, 760px body), but `SettingsSkeletonLoader` still
rendered the old flat `PageHeader` + `PageBody` — so pages painted as a
full-width flat bar then snapped into the card.

- `SettingsSkeletonLoader` now reproduces the card and **reuses the real
`SettingsPageHeader` + `SettingsPageContainer`**, so the frame aligns by
construction; the card CSS is replicated (not `SettingsPageLayout`) to
avoid the layout's side effects (hotkeys, side panel, info banner).
- It's **composed with `SettingsSectionSkeletonLoader`** so the loading
body is identical whether or not chrome is present. Rule: no chrome on
screen yet → full-page skeleton; chrome already on screen → body-only
`SettingsSectionSkeletonLoader` (the admin Enterprise tab now uses it,
matching its sibling tabs). A short comment on each component documents
this.

## 2. Application detail header — pass a plain title

`SettingsApplicationDetails` / `SettingsAvailableApplicationDetails`
passed a custom `SettingsApplicationDetailTitle` (avatar + name +
multi-line description, fixed width) into `SettingsPageLayout`'s
**centered single-line title slot**, which broke the header. They now
pass the app's display name like every other page. The available-app
"unlisted" notice moves into the body as a reusable `InlineBanner`; the
now-unused `SettingsApplicationDetailTitle` is removed.

## 3. Navigation — hide Favorites when empty

Always rendering the Favorites section (#21087) left a stray "Favorites"
title above Workspace for users with no favorites. It now renders only
when at least one favorite exists (redundant per-child guards dropped).
Note: the "+ add favorite" entry point therefore appears once you have
≥1 favorite; the first favorite is created from a record/view as before.

## Verification
- `nx typecheck twenty-front` ✅ · `oxlint` + `oxfmt --check` on changed
files ✅
- i18n catalogs intentionally untouched — handled by the repo's separate
i18n pipeline.

packages/twenty-front/src/modules/settings/admin-panel/components/SettingsAdminTabContent.tsx

@@ -5,7 +5,7 @@ import { SettingsAdminConfigVariables } from '@/settings/admin-panel/config-vari
 import { SETTINGS_ADMIN_TABS } from '@/settings/admin-panel/constants/SettingsAdminTabs';
 import { SETTINGS_ADMIN_TABS_ID } from '@/settings/admin-panel/constants/SettingsAdminTabsId';
 import { SettingsAdminHealthStatus } from '@/settings/admin-panel/health-status/components/SettingsAdminHealthStatus';
-import { SettingsSkeletonLoader } from '@/settings/components/SettingsSkeletonLoader';
+import { SettingsSectionSkeletonLoader } from '@/settings/components/SettingsSectionSkeletonLoader';
 import { activeTabIdComponentState } from '@/ui/layout/tab-list/states/activeTabIdComponentState';
 import { useAtomComponentStateValue } from '@/ui/utilities/state/jotai/hooks/useAtomComponentStateValue';
 import { lazy, Suspense } from 'react';
@@ -34,7 +34,7 @@ export const SettingsAdminTabContent = () => {
       return <SettingsAdminHealthStatus />;
     case SETTINGS_ADMIN_TABS.ENTERPRISE:
       return (
-        <Suspense fallback={<SettingsSkeletonLoader />}>
+        <Suspense fallback={<SettingsSectionSkeletonLoader />}>
           <SettingsEnterprise isAdminPanelTab />
         </Suspense>
       );