Unescaped String

Yields the result of `unescapedSource` (an Expression that evaluates to a string) as RAW content — no HTML/SVG escaping applied at the binding boundary. The evaluator marks the result with a discriminated wrapper so a surrounding Concat preserves the raw-vs-escaped distinction across joins. Used inside template fragments to splice author-trusted inner markup (e.g. an icon glyph stored in an annotation property) into a surrounding SVG or HTML template. Replaces the previous string-template `{{svg:PATH}}` function.