feat: add artplayer-plugin-audio-track for audio synchronization with video

- Implemented the audio track plugin for ArtPlayer, allowing audio to be synchronized with video playback.
- Added main functionality in `src/index.js` to handle audio playback, synchronization, and event listeners for play, pause, seek, and volume changes.
- Created TypeScript definitions for the plugin in `types/artplayer-plugin-audio-track.d.ts`.
- Included necessary build files in `dist/` for various module formats (CommonJS, ES Module, and legacy).
- Updated package metadata in `package.json` and added a README for documentation.
- Added `.npmignore` to exclude unnecessary files from the package.

docs/assets/ts/artplayer-plugin-audio-track.d.ts

@@ -0,0 +1,35 @@
+interface Option {
+  /**
+   * Audio track URL
+   */
+  url: string
+
+  /**
+   * Time offset in seconds between video and audio
+   * Positive value means audio plays ahead of video
+   * Negative value means audio plays behind video
+   * @default 0
+   */
+  offset?: number
+
+  /**
+   * Synchronization threshold in seconds
+   * @default 0.3
+   */
+  sync?: number
+}
+
+interface Result {
+  name: 'artplayerPluginAudioTrack'
+  /**
+   * The audio element
+   */
+  audio: HTMLAudioElement
+}
+
+declare const artplayerPluginAudioTrack: (option: Option) => (art: Artplayer) => Result
+
+export default artplayerPluginAudioTrack
+
+export = artplayerPluginAudioTrack;
+export as namespace artplayerPluginAudioTrack;