fix: custom Video/Audio switcher in Plugins menu (#3174)

Related to #3167

Update `setVideoState` function and `switchButtonDiv` event listener to handle transition back to audio mode.

* **Update `setVideoState` function**
  - Correctly handle the transition back to audio mode.
  - Update the `hideVideo` property in the plugin configuration.
  - Use `this.config` instead of `config` to set options and update checkbox state.

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For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/th-ch/youtube-music/issues/3167?shareId=XXXX-XXXX-XXXX-XXXX).

Author: Likhithsai2580

src/plugins/video-toggle/index.ts

@@ -179,12 +179,12 @@ export default createPlugin({
         if (this.config) {
           this.config.hideVideo = !showVideo;
         }
-        window.mainConfig.plugins.setOptions('video-toggle', config);
+        window.mainConfig.plugins.setOptions('video-toggle', this.config);
 
         const checkbox = document.querySelector<HTMLInputElement>(
           '.video-switch-button-checkbox',
         ); // custom mode
-        if (checkbox) checkbox.checked = !config.hideVideo;
+        if (checkbox) checkbox.checked = !this.config.hideVideo;
 
         if (player) {
           player.style.margin = showVideo ? '' : 'auto 0px';