Clean up namespaces (#410)

No meaningful code changes, just lots of namespace shuffling to have fewer namespaces and to put things in better namespaces.

src/ModelContextProtocol/Protocol/LoggingCapability.cs

@@ -0,0 +1,22 @@
+using ModelContextProtocol.Server;
+using System.Text.Json.Serialization;
+
+namespace ModelContextProtocol.Protocol;
+
+/// <summary>
+/// Represents the logging capability configuration for a Model Context Protocol server.
+/// </summary>
+/// <remarks>
+/// This capability allows clients to set the logging level and receive log messages from the server.
+/// See the <see href="https://github.com/modelcontextprotocol/specification/blob/main/schema/">schema</see> for details.
+/// </remarks>
+public class LoggingCapability
+{
+    // Currently empty in the spec, but may be extended in the future
+
+    /// <summary>
+    /// Gets or sets the handler for set logging level requests from clients.
+    /// </summary>
+    [JsonIgnore]
+    public Func<RequestContext<SetLevelRequestParams>, CancellationToken, ValueTask<EmptyResult>>? SetLoggingLevelHandler { get; set; }
+}