Config-driven mapping from (target_entity, target_attribute) to storage
shape (scalar/collection/relation), PHP type, and identity-key
eligibility. Replaces any name-suffix matching (e.g. _tags, _skills) —
those are convention-not-contract and reject by design.
Used by publish guards now and (in session 2) by FormBindingApplicator.
Refs: RFC-WS-6.md §4 (V1)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
