[FEATURE]: Expose favorite model cycling keybinds in TUI

[Oerum]

Describe the enhancement you want to request

Currently, favorite model cycling is implemented but hidden and has no default keybinds. This requires users to manually configure keybinds or use the /model command, which is less efficient.

Exposing this feature with default keybinds (Alt+C/Alt+X) and making the commands visible in the palette improves the workflow for power users who frequently switch between a set of preferred models.

Proposed changes:

• Set default keybinds to Alt+C (forward) and Alt+X (backward).
• Unhide the favorite cycle commands in the TUI app context.
• Update UI tips to mention the new shortcuts.
• Ensure macOS users see 'Option' instead of 'Alt' in the UI.

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• No issue template was used. This appears to be a feature request, but it is missing the required [FEATURE]: title prefix and the verification checkbox that the Feature Request template requires.
• Please resubmit using the Feature Request template, which includes a description of the problem/need and a verification checkbox.

Please edit this issue to address the above within 2 hours, or it will be automatically closed.

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This issue might be a duplicate of existing issues. Please check:

• model_cycle_favorite / model_cycle_favorite_reverse commands are no longer keybindable #5198: model_cycle_favorite / model_cycle_favorite_reverse commands were previously removed from being keybindable — this issue tracks re-exposing those same commands with default keybinds.

For keybind-related issues, please also check our pinned keybinds documentation: #4997

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

Thanks for updating the issue! It now follows the contributing guidelines and feature request template. We appreciate you taking the time to revise it.

[ariane-emory]

I don't think that default key bindings should be changed, users ought be left to bind these keys themselves if they so choose.