feat: api spec intrinsic

[thantos]

Add APISpecification.generate intrinsic to allow access to the Open API Spec from within the handlers/commands/etc.

Primary use case is to supply the api spec via a command for situations like an openai plugin.

export const specCommand = command(
  "specCommand",
  async (): Promise<openapi.OpenAPIObject> => {
    return ApiSpecification.generate();
  }
);