Codex App: add /keymap slash-command parity with the TUI

What variant of Codex are you using?

App (Codex Desktop)

What feature would you like to see?

Add a /keymap slash command to Codex Desktop, mirroring the command available in the TUI.

The minimum useful implementation could be a lightweight navigation command:

1. /keymap appears in the Desktop slash-command picker.
2. Selecting it is handled locally and does not send a model turn.
3. It opens Settings -> Keyboard Shortcuts, ideally focusing the shortcut search field.
4. Returning from Settings takes the user back to the current thread as usual.

This does not need to port the TUI picker or make Desktop use the TUI's [tui.keymap] configuration. Desktop already has a native Keyboard Shortcuts settings page and its own ~/.codex/keybindings.json; /keymap can simply provide a discoverable route to that existing UI.

The TUI now provides /keymap as the guided entry point for inspecting and editing shortcuts. Offering the same command vocabulary in Desktop would keep the two Codex interfaces closer in functionality, make shortcut customization easier to discover, and reduce friction for users who move between them.

Additional information

The original configurable-hotkeys request was closed as shipped by @fcoury-oai in https://github.com/openai/codex/issues/3049#issuecomment-4364343615, based on these two merged TUI PRs:

• https://github.com/openai/codex/pull/18593
• added the configurable keymap foundation
• https://github.com/openai/codex/pull/18594
• added the /keymap slash command and guided shortcut picker

This request is specifically for Desktop parity at the slash-command/UX level. The existing settings page is already sufficient as the destination, so the initial implementation can remain narrowly scoped.