gn-vgantt — complete planning surface
A host ships a data provider and a single (commit) callback. Bar drag, link draw, inline edit,
reorder, reparent, and propose-to-fix all land in one payload.
- Virtualized D3 timeline synced to gn-vtable outline rows
- Dependency DnD with orthogonal end→start previews
- Critical-path highlight on click (CPM, zero total float)
- Kind graph guards for legal parents, ranks, and same-kind links
- HTTP mode stays O(viewport): domain + links for visible ids only