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/services/ChainService.ts

@@ -0,0 +1,259 @@
+// src/main/services/ChainService.ts
+// Phase 10.4: Multi-LLM Chain 서비스.
+// LLMChain을 electron-store에 저장하고, 체인을 순차 실행한다.
+
+import { nanoid } from 'nanoid'
+import { getLogger } from './LoggerService'
+import { configGet } from './ConfigService'
+import { getCustomInstructionService } from './CustomInstructionService'
+import { getLocalLLMService } from './LocalLLMService'
+import { getMainWindow } from '../windows/WindowManager'
+import { IPC_CHANNELS } from '@shared/ipc-channels'
+import { D3ROError, ErrorCode } from '@shared/errors'
+import type {
+  LLMChain,
+  ChainStep,
+  CreateChainParams,
+  UpdateChainParams,
+  ChainProgress,
+  ChainExecutionResult
+} from '@shared/types'
+
+const logger = getLogger('chain-service')
+
+// ============================================================
+// 저장소 (electron-store, CustomInstructionService 패턴)
+// ============================================================
+
+let chains: LLMChain[] = []
+let initialized = false
+
+function loadChains(): LLMChain[] {
+  try {
+    const stored = configGet('llmChains' as never) as LLMChain[] | undefined
+    if (Array.isArray(stored) && stored.length > 0) {
+      return stored
+    }
+  } catch {
+    // 첫 실행 시 키가 없을 수 있음
+  }
+  return []
+}
+
+function saveChains(): void {
+  try {
+    // eslint-disable-next-line @typescript-eslint/no-require-imports
+    const { configSet } = require('./ConfigService') as {
+      configSet: (key: never, value: never) => void
+    }
+    configSet('llmChains' as never, chains as never)
+  } catch (error) {
+    logger.warn(
+      `Failed to save chains: ${error instanceof Error ? error.message : String(error)}`
+    )
+  }
+}
+
+/** 메인 윈도우 렌더러에 IPC 이벤트 전송 */
+function sendProgressToRenderer(progress: ChainProgress): void {
+  const win = getMainWindow()
+  if (win && !win.isDestroyed()) {
+    win.webContents.send(IPC_CHANNELS.CHAIN.PROGRESS, progress)
+  }
+}
+
+// ============================================================
+// ChainService
+// ============================================================
+
+class ChainService {
+  private _cancelRequested = false
+
+  initialize(): void {
+    if (initialized) return
+    chains = loadChains()
+    initialized = true
+    logger.info(`ChainService initialized (${chains.length} chains)`)
+  }
+
+  getAll(): LLMChain[] {
+    return [...chains]
+  }
+
+  getById(id: string): LLMChain | null {
+    return chains.find((c) => c.id === id) ?? null
+  }
+
+  create(params: CreateChainParams): LLMChain {
+    const now = Date.now()
+    const chain: LLMChain = {
+      id: nanoid(),
+      name: params.name,
+      steps: params.steps,
+      createdAt: now,
+      updatedAt: now
+    }
+
+    chains.push(chain)
+    saveChains()
+    logger.info(`Chain created: "${chain.name}" (${chain.steps.length} steps)`)
+    return chain
+  }
+
+  update(params: UpdateChainParams): LLMChain {
+    const index = chains.findIndex((c) => c.id === params.id)
+    if (index === -1) {
+      throw new D3ROError(ErrorCode.ChainNotFound, `Chain not found: ${params.id}`)
+    }
+
+    const existing = chains[index]
+    const updated: LLMChain = {
+      ...existing,
+      name: params.name ?? existing.name,
+      steps: params.steps ?? existing.steps,
+      updatedAt: Date.now()
+    }
+
+    chains[index] = updated
+    saveChains()
+    logger.info(`Chain updated: "${updated.name}"`)
+    return updated
+  }
+
+  delete(id: string): void {
+    const index = chains.findIndex((c) => c.id === id)
+    if (index === -1) {
+      throw new D3ROError(ErrorCode.ChainNotFound, `Chain not found: ${id}`)
+    }
+
+    const removed = chains.splice(index, 1)[0]
+    saveChains()
+    logger.info(`Chain deleted: "${removed.name}"`)
+  }
+
+  /**
+   * 체인을 순차 실행한다.
+   * 각 단계마다 CustomInstruction의 프롬프트로 LLM을 호출하고,
+   * 이전 단계 결과를 다음 단계의 입력으로 전달한다.
+   */
+  async execute(chainId: string, inputText: string): Promise<ChainExecutionResult> {
+    const chain = this.getById(chainId)
+    if (!chain) {
+      throw new D3ROError(ErrorCode.ChainNotFound, `Chain not found: ${chainId}`)
+    }
+
+    if (chain.steps.length === 0) {
+      throw new D3ROError(ErrorCode.ChainExecutionFailed, 'Chain has no steps')
+    }
+
+    this._cancelRequested = false
+    const startTime = Date.now()
+    const stepResults: Array<{ instructionId: string; output: string; durationMs: number }> = []
+    let previousOutput = inputText
+
+    const llm = getLocalLLMService()
+    const instructionService = getCustomInstructionService()
+
+    logger.info(
+      `Executing chain "${chain.name}" (${chain.steps.length} steps) with input length ${inputText.length}`
+    )
+
+    for (let i = 0; i < chain.steps.length; i++) {
+      // 취소 확인
+      if (this._cancelRequested) {
+        logger.info(`Chain execution cancelled at step ${i + 1}/${chain.steps.length}`)
+        throw new D3ROError(ErrorCode.ChainCancelled, 'Chain execution cancelled')
+      }
+
+      const step: ChainStep = chain.steps[i]
+      const instruction = instructionService.getById(step.instructionId)
+
+      if (!instruction) {
+        throw new D3ROError(
+          ErrorCode.ChainStepFailed,
+          `Instruction not found for step ${i + 1}: ${step.instructionId}`
+        )
+      }
+
+      // 입력 소스 결정
+      const stepInput = step.inputSource === 'original' ? inputText : previousOutput
+
+      // 진행 상황 전송
+      const progress: ChainProgress = {
+        chainId,
+        currentStep: i + 1,
+        totalSteps: chain.steps.length,
+        stepName: instruction.name,
+        intermediateText: previousOutput
+      }
+      sendProgressToRenderer(progress)
+
+      // LLM 호출
+      const stepStart = Date.now()
+      try {
+        const result = await llm.processText(stepInput, 'custom', undefined, instruction.prompt)
+        const stepDuration = Date.now() - stepStart
+
+        stepResults.push({
+          instructionId: step.instructionId,
+          output: result,
+          durationMs: stepDuration
+        })
+        previousOutput = result
+
+        logger.info(
+          `Chain step ${i + 1}/${chain.steps.length} ("${instruction.name}") completed in ${stepDuration}ms`
+        )
+      } catch (error) {
+        if (error instanceof D3ROError && error.code === ErrorCode.ChainCancelled) {
+          throw error
+        }
+        const msg =
+          error instanceof Error ? error.message : String(error)
+        throw new D3ROError(
+          ErrorCode.ChainStepFailed,
+          `Step ${i + 1} ("${instruction.name}") failed: ${msg}`
+        )
+      }
+    }
+
+    const totalDuration = Date.now() - startTime
+    logger.info(`Chain "${chain.name}" completed in ${totalDuration}ms`)
+
+    return {
+      chainId,
+      finalText: previousOutput,
+      steps: stepResults,
+      totalDurationMs: totalDuration
+    }
+  }
+
+  /**
+   * 진행 중인 체인 실행을 취소한다.
+   * 현재 단계가 완료된 후 다음 단계 시작 전에 중단된다.
+   */
+  cancelExecution(): void {
+    this._cancelRequested = true
+    // LLM 생성도 취소
+    getLocalLLMService().cancelGeneration()
+    logger.info('Chain execution cancel requested')
+  }
+
+  dispose(): void {
+    this._cancelRequested = true
+    logger.info('ChainService disposed')
+  }
+}
+
+// ============================================================
+// 싱글톤
+// ============================================================
+
+let instance: ChainService | null = null
+
+export function getChainService(): ChainService {
+  if (!instance) {
+    instance = new ChainService()
+  }
+  return instance
+}