agent_ui: Add some more design tweaks to the sandbox tooltip (#60085)

Quick follow up to https://github.com/zed-industries/zed/pull/59980 with
some adjustments.

Release Notes:

- N/A
c070f7c8ceDanilo Leal committed on 6/29/2026, 2:27:44 PM· committed by GitHubparent26ee53e
2 files changedLine totals unavailable