Roots capability support (#12)

Notification sending support

src/mcpdotnet/Protocol/Types/Root.cs

@@ -0,0 +1,22 @@
+namespace McpDotNet.Protocol.Types;
+
+/// <summary>
+/// Represents a root URI and its metadata.
+/// </summary>
+public class Root
+{
+    /// <summary>
+    /// The URI of the root.
+    /// </summary>
+    public required string Uri { get; init; }
+
+    /// <summary>
+    /// A human-readable name for the root.
+    /// </summary>
+    public string? Name { get; init; }
+
+    /// <summary>
+    /// Additional metadata for the root. Reserved by the protocol for future use.
+    /// </summary>
+    public object? Meta { get; init; }
+}