feat: local offline voice models (sherpa-onnx) with model manager and wake word (v2.1.0)

- electron/voice: model catalog (Whisper base/small/turbo, SenseVoice, Kokoro v1.0,
  Piper fr), streaming tar.bz2 downloader with progress, sherpa-onnx worker running in
  an Electron utilityProcess (transcribe / synthesize / status / unload), IPC + bridge.
- Renderer: 'local' providers for STT and TTS, Settings → Modèles locaux (download,
  progress, delete, activate), speaker selection, hands-free wake word with a tolerant
  matcher (accents, punctuation, edit distance) and attention window after a bare wake word.
- Packaging: native addon and worker unpacked from the asar; release 2.1.0.

Validated on Linux: Kokoro (fr) → Whisper base round trip, Piper (fr) → Whisper round trip.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017Wn5VX9HNbJ7N54hR24u9Y

electron/voice/ipc.ts

@@ -0,0 +1,22 @@
+import { ipcMain } from 'electron';
+import { VOICE_IPC, type SynthesizeRequest, type TranscribeRequest } from '../../shared/voice';
+import { engineStatus, synthesize, transcribe, unload } from './engine';
+import { cancelDownload, downloadModel, listModels, removeModel } from './models';
+
+export function registerVoiceIpc(): void {
+  ipcMain.handle(VOICE_IPC.status, () => engineStatus());
+  ipcMain.handle(VOICE_IPC.modelsList, () => listModels());
+  ipcMain.handle(VOICE_IPC.modelsDownload, (event, id: string) => downloadModel(id, event.sender));
+  ipcMain.handle(VOICE_IPC.modelsCancel, (_e, id: string) => {
+    cancelDownload(id);
+    return true;
+  });
+  ipcMain.handle(VOICE_IPC.modelsRemove, async (_e, id: string) => {
+    await unload(id).catch(() => undefined);
+    await removeModel(id);
+    return listModels();
+  });
+  ipcMain.handle(VOICE_IPC.transcribe, (_e, req: TranscribeRequest) => transcribe(req));
+  ipcMain.handle(VOICE_IPC.synthesize, (_e, req: SynthesizeRequest) => synthesize(req));
+  ipcMain.handle(VOICE_IPC.unload, (_e, id?: string) => unload(id));
+}