Collision-aware paper-chip labels

[manutej]

Why

v1 pushes labels radially and only names the topmost layer. Dense slices (L3 especially) still stack in isometric projection.

Files likely to change

• src/components/sheaf/canvas/Scene.tsx
• optionally a DOM overlay instead of drei Html

Definition of done

• No two chips overlap more than ~20% of their bounding boxes in the default camera.
• Selected + hovered labels always win.
• Labels still pointer-events: none so they cannot trap the dock.
• Screenshot of default lattice and of a selected stalk.