This PR adds some design refinements to the thinking effort selector (to be generally rolled out soon): - Improved split button UI styles and consistency with other dropdowns in the message editor - Stopped rendering the effort selector if thinking is turned off - Added a keybinding to trigger the effort menu - Added a keybinding to cycle through effort options <img width="500" height="380" alt="Screenshot 2026-02-09 at 10 18@2x" src="https://github.com/user-attachments/assets/48d5b65c-7256-4ceb-aab2-35869f8fbf4a" /> --- - [x] Code Reviewed - [x] Manual QA Release Notes: - N/A