Marshal and unmarshal both use the base62 KSUID string, replacing the
legacy JSON object wrapper and aligning gqlgen scalar behavior.
Co-authored-by: Cursor <cursoragent@cursor.com>
Expand README with setup and API guidance, add CHANGELOG breaking
section, and refresh package documentation for the V1 API surface.
Co-authored-by: Cursor <cursoragent@cursor.com>