Add a custom admin view over the technologies collection so staff can model
prerequisites as a left-to-right tree instead of a flat list.
- React Flow v12 canvas with category bands, OR-prerequisite edges, a
lite side-panel editor, and a quick-create dialog.
- Propagating layout: a technology with prerequisites lands one column right
of its parents at their average row; uncategorized roots fill a catalog
grid keyed by each tech's rank among all uncategorized technologies, so
promoting one into the tree leaves an empty slot instead of re-shuffling
the grid.
- Stability contract: connecting or removing edges never moves a card (the
connected node is pinned to its current spot), and a "Save positions"
control commits every on-screen node so the arrangement survives reload;
"Auto-arrange" clears manual positions and restores the ordered layout.
- Progression-path edge colors and per-source lanes keep overlapping edges
readable. Wire the view and its nav entry into payload.config.ts and add
dark React Flow / scrollbar styling.
