Phase 1+2 구현: Electron 뼈대 + STT/핫키/오케스트레이터

Phase 1:
- 프로젝트 초기화 (TypeScript strict, electron-vite, ESLint, Prettier)
- shared 타입 (ipc-channels 113채널, types, errors, constants)
- 메인 프로세스 뼈대 (bootstrap, lifecycle, 단일 인스턴스)
- LoggerService, ConfigService (electron-store ESM dynamic import)
- React 19 + MUI 7 Dashboard, 시스템 트레이

Phase 2:
- AudioCaptureService (node-record-lpcm16, PCM16 16kHz mono)
- HotkeyService (uiohook-napi, 더블프레스, holdMode/toggleMode)
- LocalSTTService (faster-whisper Python sidecar, 이중 조건 플러시)
- VoiceModeService 오케스트레이터 (이중 상태머신, Action Queue)
- Python sidecar (FastAPI: health/load/transcribe/shutdown)
- IPC 핸들러 (voice, stt, hotkey) + Preload API 확장

src/renderer/App.tsx

@@ -0,0 +1,26 @@
+// src/renderer/App.tsx — 루트 컴포넌트
+
+import { useState, useMemo } from 'react'
+import { ThemeProvider, CssBaseline, useMediaQuery } from '@mui/material'
+import { lightTheme, darkTheme } from './theme'
+import { AppLayout } from './components/AppLayout'
+import type { ThemeMode } from '@shared/types'
+
+export function App(): React.ReactElement {
+  const [themeMode] = useState<ThemeMode>('auto')
+  const prefersDark = useMediaQuery('(prefers-color-scheme: dark)')
+
+  const theme = useMemo(() => {
+    if (themeMode === 'auto') {
+      return prefersDark ? darkTheme : lightTheme
+    }
+    return themeMode === 'dark' ? darkTheme : lightTheme
+  }, [themeMode, prefersDark])
+
+  return (
+    <ThemeProvider theme={theme}>
+      <CssBaseline />
+      <AppLayout />
+    </ThemeProvider>
+  )
+}