nornir-escape

The ONE shared markup-escaping primitive for the nordisk constellation — XML/SVG entity escaping (`xml` → `& < > "` become `&amp; &lt; &gt; &quot;`, allocation-free `Cow` when the input is already clean). REUSE (LAW #5): seven BYTE-IDENTICAL `xml_escape`/`svg_escape` copies grew independently across nornir (viz `diagram`/`coverage_metrics_svg`, `arch`, `mimir`, `nornir-introspect`), edda (`nornir-testmatrix` coverage SVG) and Skidbladnir (`msi` WXS) — this leaf owns the canon so every SVG/XML emitter escapes the same four entities identically. std-only, ZERO runtime deps. Domain-coupled escapers (typst markdown→typst conversion, markdown table cells, asset-name slugs) STAY in their conductor (L5a).