fix: unblock input after ESC cancel, suppress abort errors, add hint

- Use Promise.race in handleSlashCommand so ESC abort immediately
  unblocks the submitQuery await chain (fixes /compress blocking input)
- Suppress abort error messages in /compress and /summary when
  cancelled via ESC (cancelSlashCommand already shows "Command cancelled")
- Add "(esc to cancel)" hint below pending slash command items
- Add i18n translations for the new hint in all 6 locales

packages/cli/src/ui/AppContainer.tsx

@@ -558,6 +558,7 @@ export const AppContainer = (props: AppContainerProps) => {
     historyManager.loadHistory,
     refreshStatic,
     toggleVimEnabled,
+    isProcessing,
     setIsProcessing,
     setGeminiMdFileCount,
     slashCommandActions,