Inert encoding and DOM-context matrix

Each case describes a fixed source token, a normalization step, and a serialized token.

The tokens contain identifiers only. They are never interpreted as markup, script, style, a URL, or an event handler. Unknown case values are rejected without reflection.

• html-text — entity-roundtripscript-element shape label; inert server-defined canary.
• quoted-attribute-text — quote-normalizationevent-handler shape label; inert server-defined canary.
• url-attribute-text — scheme-canonicalizationjavascript-url shape label; inert server-defined canary.
• inert-template-text — entity-roundtripscript-element shape label; inert server-defined canary.
• data-attribute-text — percent-decodeevent-handler shape label; inert server-defined canary.
• json-data-text — unicode-roundtripjavascript-url shape label; inert server-defined canary.

Measurement marker: ARN-BOUNDARY-XSS-CONTEXT-MATRIX