A small notification sound when codex have done working[Codex IDE QOL feature]

Request: an optional completion chime when Codex finishes executing.
Why: during long runs I switch tabs or step away; a subtle sound confirms it’s done without constant checking.
Details: user-toggle in Settings; per-run mute; volume slider; respect system Do Not Disturb; optional desktop notification.
Benefits: better focus, time savings, and accessibility for users who rely on audio cues.