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

apps/desktop/src/main/ipc/stt-handlers.ts

@@ -2,12 +2,29 @@
 
 import { ipcMain } from 'electron'
 import { IPC_CHANNELS } from '@d3ro/core/ipc-channels'
-import { ipcSuccess, ipcError, ErrorCode } from '@d3ro/core/errors'
+import { ipcSuccess, ipcError, ErrorCode, D3ROError } from '@d3ro/core/errors'
 import { getLocalSTTService } from '../services/LocalSTTService'
 import { configGet, configSet } from '../services/ConfigService'
-import type { SetSTTModelParams, SetSTTLanguageParams } from '@d3ro/core/types'
+import { getMainWindow } from '../windows/WindowManager'
+import type {
+  SetSTTModelParams,
+  SetSTTLanguageParams,
+  DownloadModelParams,
+} from '@d3ro/core/types'
+
+function safeSendToRenderer(channel: string, data: unknown): void {
+  const win = getMainWindow()
+  if (win && !win.isDestroyed()) {
+    win.webContents.send(channel, data)
+  }
+}
 
 export function registerSTTHandlers(): void {
+  // 다운로드 진행률 → 렌더러
+  getLocalSTTService().on('download-progress', (payload) => {
+    safeSendToRenderer(IPC_CHANNELS.STT.DOWNLOAD_PROGRESS, payload)
+  })
+
   ipcMain.handle(IPC_CHANNELS.STT.GET_STATUS, async () => {
     try {
       const stt = getLocalSTTService()
@@ -41,6 +58,27 @@ export function registerSTTHandlers(): void {
     }
   })
 
+  ipcMain.handle(
+    IPC_CHANNELS.STT.DOWNLOAD_MODEL,
+    async (_event, params: DownloadModelParams) => {
+      try {
+        await getLocalSTTService().downloadModel(params.modelId)
+        return ipcSuccess(undefined)
+      } catch (err) {
+        if (err instanceof D3ROError) {
+          return ipcError(err.code, err.message)
+        }
+        const msg = err instanceof Error ? err.message : String(err)
+        return ipcError(ErrorCode.STTModelDownloadFailed, `Model download failed: ${msg}`)
+      }
+    },
+  )
+
+  ipcMain.handle(IPC_CHANNELS.STT.CANCEL_DOWNLOAD, async () => {
+    await getLocalSTTService().cancelDownload()
+    return ipcSuccess(undefined)
+  })
+
   ipcMain.handle(IPC_CHANNELS.STT.GET_LANGUAGE, async () => {
     return ipcSuccess(configGet('sttLanguage'))
   })