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).
A RELAX NG attribute failure now reports an undeclared attribute
("attribute @b is not allowed on <n>") separately from a declared
attribute carrying a bad value ("attribute @count on <n>: 'abc' is not a
valid integer"), quoting the value and naming its datatype by reusing the
text detail. The declared value pattern is found by matching the
attribute name through the residual.
A RELAX NG text/datatype mismatch now reports the rich datatype reason
(quoting the value and naming the type, e.g. 'abc' is not a valid
integer) and a value mismatch quotes both the actual text and the
required literal, instead of a generic "text content is not valid". The
detail is peeled from the content pattern at the failure point through
choice, group, list, and ref.
Adds RelaxNG.errors(in:) reporting every way a document fails the schema
as individual located errors with coding paths, recovering past each
failure so all of a faulty document's problems surface at once instead of
only the first. Errors carry recovery hints naming the element types
accepted at the failure point, and distinguish unexpected elements,
invalid or missing attributes, invalid text/datatype content, and missing
required content. RelaxNG.validation() exposes the schema as a
Validation<Node, Void>, composing with the same framework as the XSD,
DTD, and Schematron rules. The boolean derivative engine remains the
authority on validity; the diagnostic walk only places and explains the
failures, recovering each step so it never cascades. Splits the engine
and the diagnostics into separate files.
