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.

src/__Libraries/StellaOps.Microservice.SourceGen/DiagnosticDescriptors.cs

@@ -52,4 +52,37 @@ internal static class DiagnosticDescriptors
         category: Category,
         defaultSeverity: DiagnosticSeverity.Info,
         isEnabledByDefault: false);
+
+    /// <summary>
+    /// Schema generation failed for a type.
+    /// </summary>
+    public static readonly DiagnosticDescriptor SchemaGenerationFailed = new(
+        id: "STELLA005",
+        title: "Schema generation failed",
+        messageFormat: "Failed to generate JSON Schema for type '{0}' in endpoint '{1}'",
+        category: Category,
+        defaultSeverity: DiagnosticSeverity.Warning,
+        isEnabledByDefault: true);
+
+    /// <summary>
+    /// [ValidateSchema] applied to non-typed endpoint.
+    /// </summary>
+    public static readonly DiagnosticDescriptor ValidateSchemaOnRawEndpoint = new(
+        id: "STELLA006",
+        title: "ValidateSchema on raw endpoint",
+        messageFormat: "[ValidateSchema] on class '{0}' is ignored because it implements IRawStellaEndpoint",
+        category: Category,
+        defaultSeverity: DiagnosticSeverity.Warning,
+        isEnabledByDefault: true);
+
+    /// <summary>
+    /// External schema resource not found.
+    /// </summary>
+    public static readonly DiagnosticDescriptor SchemaResourceNotFound = new(
+        id: "STELLA007",
+        title: "Schema resource not found",
+        messageFormat: "External schema resource '{0}' not found for endpoint '{1}'",
+        category: Category,
+        defaultSeverity: DiagnosticSeverity.Warning,
+        isEnabledByDefault: true);
 }