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

scripts/build-electron.mjs

@@ -7,13 +7,18 @@ import { rmSync } from 'node:fs';
 rmSync('dist-electron', { recursive: true, force: true });
 
 await build({
-  entryPoints: ['electron/main.ts', 'electron/preload.ts'],
+  entryPoints: {
+    main: 'electron/main.ts',
+    preload: 'electron/preload.ts',
+    'voice-worker': 'electron/voice/worker.ts'
+  },
   outdir: 'dist-electron',
   bundle: true,
   platform: 'node',
   format: 'cjs',
   target: 'node22',
-  external: ['electron'],
+  // sherpa-onnx-node stays external: it is a native addon shipped unpacked from the asar.
+  external: ['electron', 'sherpa-onnx-node'],
   sourcemap: false,
   logLevel: 'info'
 });