ConstReadonlyXLANG: 0Cross-language (Fory XLANG). Default and recommended.
ReadonlyNATIVE: 1Language-native. Only for LocalTransport (same trust domain).
ReadonlyROW: 2Row-oriented. For random-access reads.
ReadonlyJSON: 3JSON over UTF-8. Cross-language fallback. The TypeScript binding uses this exclusively because Fory JS is not yet XLANG-compliant.
Serialization mode for Fory codec.