Create @mediabunny/mp3-encoder, restructure and extend build system

packages/mp3-encoder/src/shared.ts

@@ -0,0 +1,42 @@
+/*!
+ * Copyright (c) 2025-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+export type WorkerCommand = {
+	type: 'init';
+	data: {
+		numberOfChannels: number;
+		sampleRate: number;
+		bitrate: number;
+	};
+} | {
+	type: 'encode';
+	data: {
+		audioData: ArrayBuffer;
+		numberOfFrames: number;
+	};
+} | {
+	type: 'flush';
+};
+
+export type WorkerResponseData = {
+	success: boolean;
+} | {
+	encodedData: ArrayBuffer;
+} | {
+	flushedData: ArrayBuffer;
+};
+
+export type WorkerResponse = {
+	id: number;
+} & ({
+	success: true;
+	data: WorkerResponseData;
+} | {
+	success: false;
+	error: unknown;
+});