findAllUnused

Return all blocks that are not attached to any scene.

A block is considered unused when it has no path to a scene (no scene reference and no ancestor that belongs to a scene) and is not itself a scene. Generated blocks and render blocks (fills, effects, shapes, blurs) are excluded, matching the behaviour of findAll.

This is useful for cleanup workflows and for filtering the URIs returned by EditorApi.findAllMediaURIs before relocating resources.