Unread workspace shortcuts in cmux

cmux has two more shortcuts for managing unread workspaces when agents finish at the same time.

Cmd+Control+U marks the current workspace as the oldest unread workspace, then jumps to the most recent unread workspace.

That sends the current workspace to the back of the unread cycle, so you can keep cycling through unread work without clearing it.

Cmd+Option+U toggles the current workspace read or unread.

This is useful when you jump to a new unread workspace with Cmd+Shift+U but need to context switch away before responding.