The OASIS/NIST section of the W3C conformance suite runs via a new
XMLCONF_ROOT-gated runner driven by the section's own manifest (parsed
with PureXML): 247/247 not-wf rejected, all 100 well-formed cases parse,
zero deviations. Closing its 24 gaps makes the DTD subset grammar
strict: exact PEReference shape, strict declaration names and keywords,
NDATA and notation tails, no bare '%' in entity values, case-sensitive
balanced conditional sections, junk between declarations rejected,
external-subset violations now propagate (with text-declaration
support, production 77), and a PI target must be separated from its
data. The xmltest baseline tightens to 181/186: CDATA in the internal
subset (107) is now rejected, five documented deviations remain.
Closes#123
