Feature Request: Jump to Latest Unread

[jwonyLee]

Summary

Add a global action to jump directly to the most recent unread notification/activity, similar to cmux.

Shortcut

⌘⇧U

Behavior

•	Find the latest unread notification (global)
•	Switch to the correct worktree
•	Focus the correct tab/split/surface
•	Jump to the exact location (anchor)
•	Mark only that item as read (on successful jump)

Empty state

•	If no unread: show “No unread notifications” (or disable action)

Notes

•	Based on existing notification model (not message-level unread)
•	Minimal version is fine: select latest unread → jump → mark read
•	Should keep sidebar badges and notification counts in sync