* Replace forward-referenced strings with direct type annotations in `json_schema_type.py`.
* refactor(ref_type_parser): eliminate unused future annotations import
* Migrate from `typing_extensions` to `typing` for supported Python versions, and update code to use modern type hinting with unions and annotations.
* Update type hinting to use lowercase generics for Python 3.9+ compatibility.
* Remove redundant comments in type parsers and tests
* Clean up redundant comments in `test_oneof_type_parser.py`
* Remove redundant comments across parsers and tests
* 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* Remove outdated `oneOf` examples from docs, expand test cases and provide refined examples with discriminator support
- Adds a test to ensure required array fields without defaults are enforced as required.
- Updates `ArrayTypeParser` to correctly handle `default_factory` for required fields and fields with defaults.
