Rename ansi and prettylight colors

.changeset/fifty-apricots-sing.md

@@ -0,0 +1,12 @@
+---
+'@primer/primitives': minor
+---
+
+Migrate prettylights syntax tokens to canonical `prettylights-syntax-*` naming while preserving legacy compatibility.
+
+- Migrate ANSI colors to canonical `ansi-*` naming with deprecated `color-ansi-*` aliases.
+- Keep `codeMirror-*` tokens unchanged.
+- Add modern canonical prettylights syntax token names (for example `entityTag`, `storageModifierImport`, `stringRegexp`, `metaDiffRange`).
+- Keep legacy `color-prettylights-syntax-*` names as deprecated aliases pointing to canonical replacements.
+- Update fallback and Storybook migration artifacts to reflect canonical naming and legacy alias support.
+- Update syntax docs/guidelines output to document `prettylights-syntax-[element]` as canonical with deprecated legacy alias notes.