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.
Add the PureXML.Schema namespace validating XSD Part 2 built-in datatypes
and constraining facets. Built-ins span string/boolean/decimal, the bounded
integer family with intrinsic bounds, float/double, duration, the eight
date/time types, hexBinary, base64Binary, anyURI, QName, and the
Name/NCName/NMTOKEN/language family. Facets: length/minLength/maxLength,
pattern (via the regex engine), enumeration (value-space comparison),
whiteSpace, min/maxInclusive/Exclusive, totalDigits, fractionDigits.
Decimals compare exactly with no floating-point loss; date/time fields are
range-validated with leap years, 24:00:00, and timezone bounds.
Closes#8
