test: add comprehensive non-admin user test cases for NowPlaying visibility

Enhances test coverage by making the usePermissions mock dynamic and adding test cases that verify:
- Admin users can see NowPlayingPanel when adminOnly is true
- Non-admin users cannot see NowPlayingPanel when adminOnly is true
- Non-admin users can see NowPlayingPanel when adminOnly is false
- Non-admin users cannot see NowPlayingPanel when feature is disabled

This ensures the admin-only permission check works correctly for all user types.

ui/src/layout/AppBar.test.jsx

@@ -8,11 +8,12 @@ import AppBar from './AppBar'
 import config from '../config'
 
 let store
+let mockPermissions = 'admin'
 
 vi.mock('react-admin', () => ({
   AppBar: ({ userMenu }) => <div data-testid="appbar">{userMenu}</div>,
   useTranslate: () => (x) => x,
-  usePermissions: () => ({ permissions: 'admin' }),
+  usePermissions: () => ({ permissions: mockPermissions }),
   getResources: () => [],
 }))
 
@@ -40,6 +41,7 @@ describe('<AppBar />', () => {
     config.devActivityPanel = true
     config.enableNowPlaying = true
     config.nowPlayingAdminOnly = true
+    mockPermissions = 'admin'
     store = createStore(combineReducers({ activity: activityReducer }), {
       activity: { nowPlayingCount: 0 },
     })
@@ -73,4 +75,67 @@ describe('<AppBar />', () => {
     )
     expect(screen.getByTestId('now-playing-panel')).toBeInTheDocument()
   })
+
+  describe('admin-only mode', () => {
+    beforeEach(() => {
+      config.nowPlayingAdminOnly = true
+    })
+
+    it('shows NowPlayingPanel to admin users', () => {
+      mockPermissions = 'admin'
+      render(
+        <Provider store={store}>
+          <AppBar />
+        </Provider>,
+      )
+      expect(screen.getByTestId('now-playing-panel')).toBeInTheDocument()
+    })
+
+    it('hides NowPlayingPanel from non-admin users', () => {
+      mockPermissions = 'user'
+      render(
+        <Provider store={store}>
+          <AppBar />
+        </Provider>,
+      )
+      expect(screen.queryByTestId('now-playing-panel')).toBeNull()
+    })
+  })
+
+  describe('non-admin users', () => {
+    beforeEach(() => {
+      mockPermissions = 'user'
+    })
+
+    it('cannot see NowPlayingPanel when adminOnly is true', () => {
+      config.nowPlayingAdminOnly = true
+      render(
+        <Provider store={store}>
+          <AppBar />
+        </Provider>,
+      )
+      expect(screen.queryByTestId('now-playing-panel')).toBeNull()
+    })
+
+    it('can see NowPlayingPanel when adminOnly is false', () => {
+      config.nowPlayingAdminOnly = false
+      render(
+        <Provider store={store}>
+          <AppBar />
+        </Provider>,
+      )
+      expect(screen.getByTestId('now-playing-panel')).toBeInTheDocument()
+    })
+
+    it('cannot see NowPlayingPanel when feature is disabled', () => {
+      config.enableNowPlaying = false
+      config.nowPlayingAdminOnly = false
+      render(
+        <Provider store={store}>
+          <AppBar />
+        </Provider>,
+      )
+      expect(screen.queryByTestId('now-playing-panel')).toBeNull()
+    })
+  })
 })