Purpose:
This package is a facade for the Headless ecosystem.
It re-exports core contracts and a “reasonable default” set of components.

Non-goals:
- No reverse dependencies: other packages must not depend on this facade.

Invariants:
- Facade only re-exports; it must not contain behavior logic.
- Keep exports stable; changes should be additive in minor.

Correct usage:
- Apps typically depend on `headless` instead of importing many packages.

Anti-patterns:
- Making components import the facade.

