dsh-api-testgen: API Test Skeleton Generation Based on OpenAPI 3.x

The `dsh-api-testgen` plugin for DSH Harness is designed to address the repetitive and error-prone nature of writing API tests. By parsing OpenAPI 3.x specifications, it automatically generates test code skeletons that cover successful, missing-parameter, and invalid-enum scenarios. It supports both Python (pytest) and TypeScript (vitest) and runs entirely locally. Developers can use the plugin to quickly build an automated testing system and, in combination with other DSH plugins, create a closed API development loop. Note that the generated code includes only basic assertions; business-specific logic must be added manually.