fix(enterprise): message nav hovercard and active state

[OpeOginni]

Issue for this PR

Closes #23958

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

• packages/ui/src/components/message-nav.tsx: replaced the Tooltip wrapper with an inline hovercard that stays open while the pointer is inside either the trigger or the panel. Added pointerenter/leave + focusin/out handlers with a small close delay.
• packages/ui/src/components/message-nav.css:
  • Added z-index: 1000 to the hovercard root so it sits above other page layers.
  • Capped max-height with scroll (min(480px, calc(100vh - 6rem))).
  • Made the active tick bar thicker (2px) and full-width.
  • Added background-color + font-weight: 500 highlight for the active item in the list.

How did you verify your code works?

Tested with the enterprise package ran on my local machine, and making shared sessions fallback to the production share api https://opncd.ai/api/share/<id>/data

Screenshots / recordings

BEFORE

Screen.Recording.2026-04-23.at.11.12.01.mov

AFTER

Screen.Recording.2026-04-23.at.11.56.49.mov

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[OpeOginni]

Screen.Recording.2026-05-20.at.17.58.29.mov

Made updates to use the Kobalte HoverCard component, and also show the start of the prompt as the Title of the Message rather than the previous "New Message" for every item.