Unify animations (#3729)

Unify the animation in a single code and add the CTRL + . in the
onboarding

codex-rs/tui/src/lib.rs

@@ -32,6 +32,7 @@ mod app;
 mod app_backtrack;
 mod app_event;
 mod app_event_sender;
+mod ascii_animation;
 mod backtrack_helpers;
 mod bottom_pane;
 mod chatwidget;