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/hooks/use-music.ts

@@ -1,11 +0,0 @@
-import React from 'react';
-
-import { AudioContext } from '@/contexts/songs';
-
-const useMusic = () => {
-  const music = React.useContext(AudioContext);
-
-  return music;
-};
-
-export default useMusic;