feat(V2-1a): Monorepo 구조 전환 — apps/desktop으로 V1 이동

- npm workspaces 루트 (apps/*, packages/*) 세팅
- V1 전체를 apps/desktop/으로 git mv (src, resources, tests, sidecar,
  scripts, electron.vite.config.ts, electron-builder.yml, vitest.config.ts,
  tsconfig.node.json, tsconfig.web.json)
- apps/desktop/package.json 신규 (name=@d3ro/desktop)
- productName: 'd3ro-voice' 명시 — app.getName()을 고정하여 userData 경로
  %APPDATA%\d3ro-voice\ 그대로 유지 (기존 DB/설정 연속성 보장)
- 루트 package.json을 workspace 루트로 재구성, 공통 devDep만 유지
  (typescript, eslint, prettier)
- turbo.json, tsconfig.base.json 추가 (Turborepo 자체 설치는 별도 sub-phase)
- memory/project_status.md 생성 (규칙 13)

검증:
- npm run typecheck 통과
- npm run build 통과 (electron-vite main+preload+renderer)
- npm run dev 실제 실행 → DB/핫키/Ollama 자동 실행 모두 정상

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

@@ -0,0 +1,101 @@
+// src/main/ipc/audio-handlers.ts
+
+import { ipcMain } from 'electron'
+import { IPC_CHANNELS } from '@shared/ipc-channels'
+import { ipcSuccess, ipcError, ErrorCode } from '@shared/errors'
+import { getAudioCaptureService, calculateRMS } from '../services/AudioCaptureService'
+import { getMainWindow } from '../windows/WindowManager'
+import { configGet, configSet } from '../services/ConfigService'
+import { getLogger } from '../services/LoggerService'
+import type { SetDeviceParams } from '@shared/types'
+
+const logger = getLogger('audio-handlers')
+
+let testTimer: ReturnType<typeof setTimeout> | null = null
+let testAudioHandler: ((payload: { buffer: Buffer; timestamp: number }) => void) | null = null
+let testLevelInterval: ReturnType<typeof setInterval> | null = null
+let testLastRms = 0
+
+function stopAudioTest(): void {
+  const service = getAudioCaptureService()
+  if (testAudioHandler) {
+    service.off('audio-data', testAudioHandler)
+    testAudioHandler = null
+  }
+  if (testLevelInterval) {
+    clearInterval(testLevelInterval)
+    testLevelInterval = null
+  }
+  if (testTimer) {
+    clearTimeout(testTimer)
+    testTimer = null
+  }
+  testLastRms = 0
+  service.stop().catch(() => { /* ignore */ })
+}
+
+export function registerAudioHandlers(): void {
+  ipcMain.handle(IPC_CHANNELS.AUDIO.GET_DEVICES, async () => {
+    try {
+      const devices = await getAudioCaptureService().getDevices()
+      return ipcSuccess(devices)
+    } catch {
+      return ipcError(ErrorCode.AudioDeviceNotFound, 'Failed to enumerate audio devices')
+    }
+  })
+
+  ipcMain.handle(IPC_CHANNELS.AUDIO.GET_SELECTED_DEVICE, async () => {
+    return ipcSuccess(configGet('selectedDeviceId'))
+  })
+
+  ipcMain.handle(IPC_CHANNELS.AUDIO.SET_SELECTED_DEVICE, async (_event, params: SetDeviceParams) => {
+    try {
+      configSet('selectedDeviceId', params.deviceId)
+      return ipcSuccess(undefined)
+    } catch {
+      return ipcError(ErrorCode.AudioDeviceNotFound, 'Failed to set device')
+    }
+  })
+
+  ipcMain.handle(IPC_CHANNELS.AUDIO.TEST_DEVICE, async () => {
+    try {
+      // 이전 테스트가 진행 중이면 정리
+      stopAudioTest()
+
+      const service = getAudioCaptureService()
+      await service.start()
+
+      // 오디오 데이터에서 RMS 추적
+      testAudioHandler = (payload: { buffer: Buffer; timestamp: number }) => {
+        testLastRms = calculateRMS(payload.buffer)
+      }
+      service.on('audio-data', testAudioHandler)
+
+      // 100ms 간격으로 레벨을 렌더러에 전송
+      testLevelInterval = setInterval(() => {
+        const level = testLastRms > 0 ? Math.min(1.0, Math.pow(testLastRms, 0.28)) : 0
+        const win = getMainWindow()
+        if (win && !win.isDestroyed()) {
+          win.webContents.send('audio:testLevel', { level })
+        }
+      }, 100)
+
+      // 5초 후 자동 중지
+      testTimer = setTimeout(() => {
+        stopAudioTest()
+        const win = getMainWindow()
+        if (win && !win.isDestroyed()) {
+          win.webContents.send('audio:testLevel', { level: 0 })
+        }
+      }, 5000)
+
+      return ipcSuccess({ averageLevel: 0, peakLevel: 0, hasAudio: true })
+    } catch (err) {
+      stopAudioTest()
+      return ipcError(
+        ErrorCode.AudioDeviceNotFound,
+        `Audio test failed: ${err instanceof Error ? err.message : String(err)}`,
+      )
+    }
+  })
+}