Codex App: restore Shift+Tab Plan Mode toggle

Problem

Before the recent major update, pressing Shift+Tab while typing in the chat box toggled Plan Mode on and off.

After the update, pressing Shift+Tab in the chat box no longer toggles Plan Mode as it did before. This is a regression from the previous keyboard behavior.

Expected behavior

Restore the previous behavior: pressing Shift+Tab while the chat box is focused should toggle Plan Mode on or off.

Request

Please restore the old behavior, or provide a setting that enables it.