Group @testable imports at the bottom, per public/rules-swift's swiftformat. A
behavior-preserving import-ordering reformat across 252 files (mostly tests).
--trailingclosures was deliberately not adopted (cosmetic, and swiftformat flags
it as caution-worthy).
DocumentType.validityFindings carries ValidityFinding values (reason
plus subject) instead of strings, DTDSchema.declarationErrors holds
ready ValidationErrors, and every declaration-level finding renders at
its declaration's coding path (x, r/@a) instead of at the document
root, matching the XSD consistency-errors precedent. Texts unchanged.
VC Root Element Type (root matches the DOCTYPE name), VC Unique
Element Type Declaration, VC No Duplicate Types in mixed content, VC
One ID per Element Type, VC Notation Attributes and Notation Declared,
VC Attribute Default Legal plus ID Attribute Default, lexical Name
checks for the ID family, and CDATA as character data in element
content. Strict mode adds VC Attribute Value Type (every attribute
declared; namespace declarations exempt). Declaration findings are
computed once at schema build and reported at the document root. Sun
invalid coverage moves from 43/74 to 62/74; the twelve remaining are
all the standalone='yes' family.
