refactor(main): IPC 채널 SSOT 일원화 + AppConfig 타입 강화 (WS2)

- ipc-channels.ts SSOT에 9개 그룹/키 추가: INSTRUCTION, SYSTEM_AUDIO,
  POPUP_RESULT/HISTORY/COMMAND/CAPTION, VOICE_PARTIAL, CLIPBOARD, APP,
  VOICE_CONVERSATION.FINISH_LISTENING
- WindowManager/handlers/bootstrap 하드코딩 채널 -> IPC_CHANNELS 교체.
  불일치 4건(result:* vs window:tip*)은 preload 재검증 후 SSOT로 통일.
  notifyRenderer channel: string -> IPCChannel 타입 좁힘.
- AppConfig에 7개 누락 키 추가(customInstructions, llmChains,
  voiceCommandRules, voiceCommandsEnabled, activeInstructionId,
  activeChainId, captionAudioSource) -> as never 16건 제거.
- ChainService/CustomInstructionService/WindowManager dynamic require -> static import.
- services/index.ts 데드 레지스트리 제거 (import 0건).
SKIP: ipcSuccess/ipcError 헬퍼 통일, catch 패턴(별도)
정책: docs/REFACTOR_POLICY.md DP2, DP9

apps/desktop/src/main/ipc/cloud-sync-handlers.ts

@@ -7,6 +7,7 @@ import { D3ROError, ErrorCode } from '@d3ro/core/errors'
 import type { IPCResult } from '@d3ro/core/errors'
 import { getCloudSyncService } from '../services/CloudSyncService'
 import { getLogger } from '../services/LoggerService'
+import { configSet } from '../services/ConfigService'
 
 const logger = getLogger('cloud-sync-handlers')
 
@@ -70,7 +71,7 @@ export function registerCloudSyncHandlers(): void {
   ipcMain.handle(IPC_CHANNELS.CLOUD_SYNC.PUSH_ALL, async () => {
     try {
       const result = await sync.pushAll()
-      configSet('cloudSyncLastAt' as never, Date.now() as never)
+      configSet('cloudSyncLastAt', Date.now())
       return ok(result)
     } catch (e) {
       return fail(e)
@@ -80,7 +81,7 @@ export function registerCloudSyncHandlers(): void {
   ipcMain.handle(IPC_CHANNELS.CLOUD_SYNC.PULL_ALL, async () => {
     try {
       const result = await sync.pullAll()
-      configSet('cloudSyncLastAt' as never, Date.now() as never)
+      configSet('cloudSyncLastAt', Date.now())
       return ok(result)
     } catch (e) {
       return fail(e)