* feat: prioritize worktrees with active sessions in sidebar sorting
- Active worktrees (those with sessions) are now displayed first
- Active worktrees are sorted by most recent session activity (desc)
- Inactive worktrees maintain alphabetical sorting by label
- Improves UX by surfacing actively used worktrees at the top
* fix: finalize worktree sidebar sorting
Clean up the active-session-first worktree sorting change so the sidebar behavior is ready to ship.