The two monolithic XSD content/identity rules only satisfied the OpenAPIKit
validation idiom at the wrong granularity: no per-constraint removability,
no isolable failing/near-miss tests. Split them into 32 named rules, each
finding tagged at its origin and cached per XSDContext so the walk still
runs once per document (the #101 decision against duplicating XSD's
recursive type resolution still holds). Wired the streaming path's ID/IDREF
and identity checks through the same framework instead of calling the
validators imperatively, and added the unwrapAndLookup combinator the rule
already named as required.
Also includes the mandated repo-wide swiftformat/swiftlint pass.
SchemaRedefineSelfReference.swift had reached the 400-line limit, blocking further
redefine-restriction work without a squeeze. It also mixed three cohesive concerns:
redefine self-reference well-formedness (src-redefine.6/7.2.1), attribute-group
restriction (cos-ct-restricts over the redefinition), and model-group restriction.
Move the attribute-group restriction machinery (redefineAttributeGroupRestrictionFindings
and its helpers) into SchemaRedefineAttributeGroupRestriction.swift, following the
established one-concern-per-file pattern (IdentityFieldType.swift). The shared base-
component lookups (baseComponents/resolveBaseComponent) become internal so both files
use them. Pure code move, no behaviour change: 171 + 232 lines (was 400); full suite
and the XSTS gate pass unchanged (20/0/22/0 buckets, 1558 unit tests).
