When working with multiple repositories and worktrees, users may want to see all main repositories but exclude their linked worktrees from tree views.

Impact

Users with many worktrees can reduce clutter in the Branches, Commits, Contributors, Remotes, Stashes, Tags, and Worktrees views by excluding worktrees whose main repository is also open.

Validation

1. Open a repository that has linked worktrees
2. Open the "Filter Repositories" picker in any supported view
3. Select "All Repositories (excluding worktrees)"
4. Verify only main repositories are shown, not their linked worktrees

Risk

Low - Adds a new filter option without changing existing behavior. The default remains "All Repositories".