feat(palette): unify quick open into command palette with multi-source search

Merge file picker into command palette. Single Cmd+P entry searches
files, sessions, settings pages and commands; groups re-order by best
fuzzy score per source. Sessions show branch labels; git status is
lazily fetched for all session directories on open.

Drop QuickOpenDialog and Cmd+K shortcut.

packages/ui/src/lib/i18n/messages/ko.settings.ts

@@ -718,7 +718,6 @@ export const settingsDict = {
   'settings.openchamber.keyboardShortcuts.field.pressKeys': '키를 누르세요...',
   'settings.openchamber.keyboardShortcuts.error.captureFirst': '먼저 단축키를 입력하세요.',
   'settings.openchamber.keyboardShortcuts.warning.riskyBrowserShortcut': '이 단축키는 브라우저 기본값과 충돌할 수 있습니다. 그래도 저장됩니다.',
-  'settings.openchamber.keyboardShortcuts.action.open_quick_open.label': '빠른 열기 열기',
   'settings.openchamber.keyboardShortcuts.action.open_go_to_line.label': '줄로 이동(파일 편집기)',
   'settings.openchamber.keyboardShortcuts.action.open_command_palette.label': '명령 팔레트 열기',
   'settings.openchamber.keyboardShortcuts.action.focus_input.label': '입력에 포커스',