Add unit tests for RabbitMq and Udp transport servers and clients

- Implemented comprehensive unit tests for RabbitMqTransportServer, covering constructor, disposal, connection management, event handlers, and exception handling.
- Added configuration tests for RabbitMqTransportServer to validate SSL, durable queues, auto-recovery, and custom virtual host options.
- Created unit tests for UdpFrameProtocol, including frame parsing and serialization, header size validation, and round-trip data preservation.
- Developed tests for UdpTransportClient, focusing on connection handling, event subscriptions, and exception scenarios.
- Established tests for UdpTransportServer, ensuring proper start/stop behavior, connection state management, and event handling.
- Included tests for UdpTransportOptions to verify default values and modification capabilities.
- Enhanced service registration tests for Udp transport services in the dependency injection container.

docs/api/overview.md

@@ -5,6 +5,12 @@ Last updated: 2025-11-25 (Md.V docs stream)
 ## Scope
 Shared conventions for all StellaOps HTTP APIs. Service-specific schemas live under `src/Api/StellaOps.Api.OpenApi` and composed `out/api/stella.yaml`.
 
+## Related Documentation
+
+- [OpenAPI Discovery](openapi-discovery.md) - Discovery endpoints and aggregation
+- [Schema Validation](../modules/router/schema-validation.md) - JSON Schema validation for microservice endpoints
+- [OpenAPI Aggregation](../modules/router/openapi-aggregation.md) - Gateway OpenAPI document generation
+
 ## Authentication & tenancy
 - **Auth**: Bearer tokens (`Authorization: Bearer <token>`); service accounts must include `aud` for the target service.
 - **Tenancy**: Multi-tenant endpoints require `X-Stella-Tenant` (or embedded tenant in token claims). Requests without tenant fail with `403` + `error.code = TENANT_REQUIRED`.