Tier Chip SVG

SVG fragment shown when the resource's SVG is rendered at <60px wide — favicon, tree node, breadcrumb dot. Placed inside the `<g class="tier-chip">` group. Authored as a `tx.Expression` (typically a `tx.Concat` over `tx.StringLiteral` parts interleaved with `tx.PropertyRead`, `tx.DisplayLabel`, `tx.SubjectUri`, `tx.UriName`, `tx.UnescapedString`, and `tx.Normalize` for case or first-character transforms — see kanonak.org/transformations for the full vocabulary). Each substitution resolves through the object model and is validated at `kanonak validate` time, so a bad property reference fails authoring rather than silently leaking an unresolved placeholder into rendered output. CSS variables like `var(--kan-accent)` work directly inside `tx.StringLiteral` SVG content.