* Add support for `oneOf` type parsing with validation and example cases
* Improve `oneOf` type parsing: refine validators, add discriminator support, and expand test coverage
* Add hashable and non-hashable value support to `ConstTypeParser` with expanded test cases
* Refine `field_props` check in `_type_parser` for cleaner default handling
* Update `StringTypeParser` to refine `format` handling and enrich `json_schema_extra`
* Remove outdated `oneOf` examples from docs, expand test cases and provide refined examples with discriminator support
