scientific(topic): retain fitted basis identity in document-coordinate summary #667

Finding

#664's FittedDocumentCoordinateSummary is now minted only from owner-issued ReferenceTopicFit, and construction validates the fitted topic basis. However, the summary discards that FittedTopicBasisIdentity after validation and exposes each ALR coordinate only as {numerator_topic_index, reference_topic_index, location, variance}.

That means the fit-local uncertainty/location view still requires a consumer to interpret bare topic indexes without the owner-derived fitted basis that gives those indexes numerical meaning. This is narrower than #663's release/source-vocabulary problem: the missing binding already exists inside topic_measurement and should be retained in the fit-local owner view before Analysis projection is attempted.

Required RED

Use an actual converged ReferenceTopicFit and require FittedDocumentCoordinateSummary::topic_basis_identity() to equal FittedTopicBasisIdentity::from_bound_fit(&fit). Verify that every coordinate index resolves into that retained basis and that the reference index resolves to the same fitted reference topic for every document row.

Hostile/malformed-state tests must continue to reject invalid basis rows, invalid ALR locations, dimension mismatches, and non-positive/non-finite variances.

Minimal repair

Store the validated FittedTopicBasisIdentity once at summary scope and expose it read-only. Keep per-coordinate storage normalized as local indexes + one immutable summary-level basis rather than copying SHA-256 strings into every document coordinate. No topic reordering or semantic naming.

Boundary

• scientific(topic): bind reference fit results to the admitted estimator input #665/scientific(topic): bind fitted topic-basis identity to owner-issued reference fit #666 own fit/input/model and public basis-authority integrity.
• This issue owns fit-local coordinate-summary ↔ fitted-basis binding.
• release(topic): bind topic-index coordinates to the fitted topic basis #663 still owns release-level topic coordinate binding.
• release(provenance): bind topic-lineage input to owner-issued source snapshot evidence #658/feat(evidence): own immutable source snapshot receipts #527 still own source/vocabulary provenance, so this fit-local basis remains non-authoritative outside that owner boundary.

Keep #639 Draft. No Evidence/source claim, covariance transformation, LLM interpretation, force push, destructive rebase, self-approval, or gate weakening.

Refs #638 #639 #658 #663 #664 #665 #666 ADR 0012.