Branching: snapshots now track parentId to form a tree structure.
Swapping to an old snapshot and editing forks into a new branch.
Sidebar and timeline show < 1/3 > navigators at fork points to
switch between branches. Pruning protects ancestors and fork points.
Deleting a fork point re-parents its children.
Profiles: save/load named sets of workflows as session profiles.
Backend stores profiles as JSON in data/profiles/. Sidebar has a
collapsible Profiles section with save, load, and delete.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>