Remove music player and related context/hooks

Deleted the audio player component, songs context, and use-music hook, along with all related code and configuration. Updated affected components and pages to remove music player dependencies and UI. Also improved sidebar, background, and about page UI, and refactored site config icons to use react-icons.

packages/napcat-webui-frontend/src/App.tsx

@@ -7,7 +7,6 @@ import PageLoading from '@/components/page_loading';
 import Toaster from '@/components/toaster';
 
 import DialogProvider from '@/contexts/dialog';
-import AudioProvider from '@/contexts/songs';
 
 import useAuth from '@/hooks/auth';
 
@@ -33,13 +32,11 @@ function App () {
       <Provider store={store}>
         <PageBackground />
         <Toaster />
-        <AudioProvider>
-          <Suspense fallback={<PageLoading />}>
-            <AuthChecker>
-              <AppRoutes />
-            </AuthChecker>
-          </Suspense>
-        </AudioProvider>
+        <Suspense fallback={<PageLoading />}>
+          <AuthChecker>
+            <AppRoutes />
+          </AuthChecker>
+        </Suspense>
       </Provider>
     </DialogProvider>
   );