Wire pointcloud-reconstruction into execution dispatch

[GeneralPawz]

What

Add a dispatch-pointcloud-reconstruction feature to axiolid-dispatch, registering the reference/adopted provider with fallback policy, matching dispatch-mesh-boolean/dispatch-mesh-section.

Why now

Dispatch is the only place provider selection and fallback are allowed to live (ADR 0035); without this the contract and provider exist but nothing can pick one at runtime.

Depends on

Define pointcloud-reconstruction operation contract, Add reference/adopted pointcloud reconstruction provider

Definition of done

• axiolid-dispatch gains a pointcloud-reconstruction operation registration path.
• Fallback/failure behavior matches existing mesh-boolean/mesh-section dispatch semantics.
• A mutation proves the gate catches a provider dropped from the registry.

Area

architecture