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/services/VoiceCommandService.ts

@@ -67,9 +67,8 @@ const DEFAULT_KEYWORDS: ReadonlyArray<DefaultKeywordEntry> = [
 // electron-store 키 (ConfigService와 별도 네임스페이스)
 // ============================================================
 
-// configGet/configSet에 타입이 없는 키를 사용하므로 as never 캐스팅 필요
-const STORE_KEY_RULES = 'voiceCommandRules' as never
-const STORE_KEY_ENABLED = 'voiceCommandsEnabled' as never
+const STORE_KEY_RULES: keyof import('@d3ro/core/types').AppConfig = 'voiceCommandRules'
+const STORE_KEY_ENABLED: keyof import('@d3ro/core/types').AppConfig = 'voiceCommandsEnabled'
 
 // ============================================================
 // 키워드 매칭 엔진
@@ -292,7 +291,7 @@ class VoiceCommandService {
 
   private saveRules(): void {
     try {
-      configSet(STORE_KEY_RULES, this.rules as never)
+      configSet(STORE_KEY_RULES, this.rules)
     } catch (error) {
       logger.warn(
         `Failed to save voice command rules: ${error instanceof Error ? error.message : String(error)}`
@@ -311,7 +310,7 @@ class VoiceCommandService {
 
   private saveEnabled(): void {
     try {
-      configSet(STORE_KEY_ENABLED, this.enabled as never)
+      configSet(STORE_KEY_ENABLED, this.enabled)
     } catch (error) {
       logger.warn(
         `Failed to save voice command enabled state: ${error instanceof Error ? error.message : String(error)}`