Implement response types for OpenAPI schema generation

- Add parseResponseSchema method to parse entity references from returns field
- Enhance convertMethod to generate proper response content schemas
- Add cleanReturnsField method to preserve entity names while cleaning markdown
- Create comprehensive tests for response type functionality
- Support both single entities [EntityName] and arrays Array of [EntityName]

Co-authored-by: abraham <[email protected]>

Author: Copilot