Resolve a ShapeRef to a face in the current shape.
Resolution strategy:
Exact: the role's tracked successor hashes. One survivor → exact match;
several survivors (a face that split) → disambiguate among only those
fragments; none survive → deleted.
Geometric fallback over the whole shape when the role isn't tracked (or a
scoped score turned up nothing): best-scoring face, else ambiguous /
not-found.
Resolve a ShapeRef to a face in the current shape.
Resolution strategy: