feat: implemented v1 audio-to-midi conversion (polyphonic only, algorithm-based)

src/workers/audioToMidiWorker.ts

@@ -0,0 +1,22 @@
+import {
+  detectMonophonicNotesFromAudio,
+  type AudioToMidiDetectedNote,
+  type AudioToMidiDetectionRequest,
+} from '../util/audioToMidiCore';
+
+export interface AudioToMidiWorkerResult {
+  type: 'result';
+  notes: AudioToMidiDetectedNote[];
+}
+
+type WorkerScopeLike = typeof globalThis & {
+  onmessage: ((event: MessageEvent<AudioToMidiDetectionRequest>) => void) | null;
+  postMessage: (message: AudioToMidiWorkerResult) => void;
+};
+
+const workerScope = self as WorkerScopeLike;
+
+workerScope.onmessage = (event: MessageEvent<AudioToMidiDetectionRequest>) => {
+  const notes = detectMonophonicNotesFromAudio(event.data);
+  workerScope.postMessage({ type: 'result', notes });
+};