Add TypeScript types for validation

**Description**
Currently types lacks proper serialization support.

**Proposed solution**
Add configurable serialization with sensible defaults.

**Priority**: Low/Medium

Start by locating the TypeScript types and validation code referenced by the issue, then trace how values are currently serialized. Clarify whether the goal is validation types, configurable serialization, or both, and define sensible defaults and tests before implementing; done means the supported types serialize correctly under the chosen defaults and configuration.

Written by the indexing model from the issue text.