add transcript mode (#2525)

this adds a new 'transcript mode' that shows the full event history in a
"pager"-style interface.


https://github.com/user-attachments/assets/52df7a14-adb2-4ea7-a0f9-7f5eb8235182

codex-rs/tui/src/lib.rs

@@ -49,6 +49,7 @@ mod slash_command;
 mod status_indicator_widget;
 mod streaming;
 mod text_formatting;
+mod transcript_app;
 mod tui;
 mod user_approval_widget;