feat(bootstrap): Whisper large-v3-turbo 기본 전환 + 온보딩 2단계 다운로드 진행률

- 기본 STT 모델 base → large-v3-turbo (6배 빠름, 1.6GB)
- 사이드카: /download, /download/status, /download/cancel + --models-dir
- LocalSTTService: downloadModel/cancelDownload + download-progress 이벤트
- IPC: 설계서 02의 stt:downloadModel/cancelDownload/downloadProgress 구현
- OnboardingModal: LLM(gemma4:e4b) → STT(turbo) 2단계 순차 다운로드 UI
- SettingsModal turbo 선택지 + settings.model.largeTurbo 12 locale
- 테스트: 모노레포 잔재 import 수정 (src/shared → @d3ro/core), 41/41 통과

packages/i18n/src/locales/en.json

@@ -122,6 +122,7 @@
   "settings.model.small": "small (244 MB, good)",
   "settings.model.medium": "medium (769 MB, great)",
   "settings.model.large": "large-v3 (1.5 GB, best)",
+  "settings.model.largeTurbo": "large-v3-turbo (1.6 GB, fast & accurate)",
   "settings.sttLanguage": "Recognition Language",
   "settings.sttLang.auto": "Auto-detect",
   "settings.ollamaServer": "Ollama Server",
@@ -627,5 +628,9 @@
   "onboarding.success": "Setup complete! You can now use the app.",
   "onboarding.failed": "Download failed: {{message}}",
   "onboarding.retry": "Retry",
+  "onboarding.sttModelMissing": "Speech recognition model ({{model}}) is not installed.",
+  "onboarding.sttModelSize": "Size: ~1.6GB — takes 2–10 min depending on network speed",
+  "onboarding.step": "Step {{current}}/{{total}}",
+  "onboarding.progressDetail": "{{downloaded}} / {{total}} MB",
   "onboarding.ollamaNotRunning": "Ollama server is not running. Please retry shortly."
 }