앱 시작 시 무거운 초기화 지연으로 유휴 성능 개선

앱 시작 직후 AX Agent 창을 미리 생성하던 경로를 제거하고 실제로 AX Agent를 열 때만 ChatWindow를 만들도록 정리했습니다.

런처 검색 인덱스 전체 스캔과 파일 감시 시작도 부팅 시 즉시 실행하지 않고, 런처를 실제로 표시할 때 한 번만 지연 시작하도록 변경했습니다.

README와 DEVELOPMENT 문서를 2026-04-06 17:35(KST) 기준으로 갱신했고, Release 빌드 검증에서 경고 0 오류 0을 확인했습니다.

docs/DEVELOPMENT.md

@@ -4988,3 +4988,5 @@ ow + toggle ?쒓컖 ?몄뼱濡??ㅼ떆 ?뺣젹?덈떎.
 - Document update: 2026-04-06 17:18 (KST) - `FileDialogWatcher` is no longer started at app boot when file-dialog integration is disabled. `App.xaml.cs` now toggles the global WinEvent hook through `UpdateFileDialogWatcherState()`, and `SchedulerService.cs` now self-stops when no enabled schedules remain. This directly targets the 3–5% idle CPU symptom reported while neither the launcher nor AX Agent was open.
 - Document update: 2026-04-06 17:24 (KST) - Changed the default launcher text-action profile to opt-in. `AppSettings.cs` and `SettingsViewModel.cs` now default `EnableTextAction` to `false`, and `TextActionCommands` now defaults to an empty list instead of all commands enabled.
 - Document update: 2026-04-06 17:24 (KST) - Removed the forced “at least one command must remain enabled” behavior from `SettingsWindow.xaml.cs`. The text-action command panel now allows every AI command, including `rewrite`, to be turned off, and the hint text in `SettingsWindow.xaml` now explains that the popup falls back to showing only `AX Commander 열기` when all AI commands are disabled.
+- Document update: 2026-04-06 17:35 (KST) - Reduced another startup performance hotspot in `App.xaml.cs` by removing the idle-time `PrewarmChatWindow()` path. AX Agent is no longer instantiated in the background at app startup and is created only when the user actually opens it.
+- Document update: 2026-04-06 17:35 (KST) - Changed launcher search warmup from eager startup work to on-demand initialization. `App.xaml.cs` now starts the first `IndexService.BuildAsync()` scan and `StartWatchers()` only when the launcher is actually shown through `ShowLauncherWindow()`, instead of running a full index scan and watcher hookup at boot even when the launcher is never opened.