Implement InMemory Transport Layer for StellaOps Router

- Added InMemoryTransportOptions class for configuration settings including timeouts and latency.
- Developed InMemoryTransportServer class to handle connections, frame processing, and event management.
- Created ServiceCollectionExtensions for easy registration of InMemory transport services.
- Established project structure and dependencies for InMemory transport library.
- Implemented comprehensive unit tests for endpoint discovery, connection management, request/response flow, and streaming capabilities.
- Ensured proper handling of cancellation, heartbeat, and hello frames within the transport layer.

src/__Libraries/StellaOps.Router.Common/Models/EndpointDescriptor.cs

@@ -0,0 +1,42 @@
+namespace StellaOps.Router.Common.Models;
+
+/// <summary>
+/// Describes an endpoint's identity and metadata.
+/// </summary>
+public sealed record EndpointDescriptor
+{
+    /// <summary>
+    /// Gets the name of the service that owns this endpoint.
+    /// </summary>
+    public required string ServiceName { get; init; }
+
+    /// <summary>
+    /// Gets the semantic version of the service.
+    /// </summary>
+    public required string Version { get; init; }
+
+    /// <summary>
+    /// Gets the HTTP method (GET, POST, PUT, PATCH, DELETE).
+    /// </summary>
+    public required string Method { get; init; }
+
+    /// <summary>
+    /// Gets the path template (e.g., "/billing/invoices/{id}").
+    /// </summary>
+    public required string Path { get; init; }
+
+    /// <summary>
+    /// Gets the default timeout for this endpoint.
+    /// </summary>
+    public TimeSpan DefaultTimeout { get; init; } = TimeSpan.FromSeconds(30);
+
+    /// <summary>
+    /// Gets the claim requirements for authorization.
+    /// </summary>
+    public IReadOnlyList<ClaimRequirement> RequiringClaims { get; init; } = [];
+
+    /// <summary>
+    /// Gets a value indicating whether this endpoint supports streaming.
+    /// </summary>
+    public bool SupportsStreaming { get; init; }
+}