feat: Add support for retrieving transcripts (#500)

* feat: Add support for retrieving transcripts

* chore: lint

* chore: update docs

* chore: Do not include nodes in errors thrown

* chore: Improve error messages

* fix(ExpandableMetadata): `expanded_content` type mismatch

* chore: lint

src/parser/classes/Transcript.ts

@@ -0,0 +1,15 @@
+import { YTNode } from '../helpers.js';
+import type { RawNode } from '../index.js';
+import Parser from '../index.js';
+import TranscriptSearchPanel from './TranscriptSearchPanel.js';
+
+export default class Transcript extends YTNode {
+  static type = 'Transcript';
+
+  content: TranscriptSearchPanel | null;
+
+  constructor(data: RawNode) {
+    super();
+    this.content = Parser.parseItem(data.content, TranscriptSearchPanel);
+  }
+}