Remove all obsolete APIs from codebase

src/ModelContextProtocol.Core/Client/McpClient.Methods.cs

@@ -10,9 +10,7 @@ namespace ModelContextProtocol.Client;
 /// <summary>
 /// Represents an instance of a Model Context Protocol (MCP) client session that connects to and communicates with an MCP server.
 /// </summary>
-#pragma warning disable CS0618 // Type or member is obsolete
-public abstract partial class McpClient : McpSession, IMcpClient
-#pragma warning restore CS0618 // Type or member is obsolete
+public abstract partial class McpClient : McpSession
 {
     /// <summary>Creates an <see cref="McpClient"/>, connecting it to the specified server.</summary>
     /// <param name="clientTransport">The transport instance used to communicate with the server.</param>

src/ModelContextProtocol.Core/Client/McpClient.cs

@@ -5,9 +5,7 @@ namespace ModelContextProtocol.Client;
 /// <summary>
 /// Represents an instance of a Model Context Protocol (MCP) client session that connects to and communicates with an MCP server.
 /// </summary>
-#pragma warning disable CS0618 // Type or member is obsolete
-public abstract partial class McpClient : McpSession, IMcpClient
-#pragma warning restore CS0618 // Type or member is obsolete
+public abstract partial class McpClient : McpSession
 {
     /// <summary>
     /// Gets the capabilities supported by the connected server.

src/ModelContextProtocol.Core/Client/McpClientHandlers.cs

@@ -36,7 +36,7 @@ public class McpClientHandlers
     /// </para>
     /// <para>
     /// Handlers provided via <see cref="NotificationHandlers"/> will be registered with the client for the lifetime of the client.
-    /// For transient handlers, <see cref="IMcpEndpoint.RegisterNotificationHandler"/> may be used to register a handler that can
+    /// For transient handlers, <see cref="McpSession.RegisterNotificationHandler"/> may be used to register a handler that can
     /// then be unregistered by disposing of the <see cref="IAsyncDisposable"/> returned from the method.
     /// </para>
     /// </remarks>

src/ModelContextProtocol.Core/Client/McpClientImpl.cs

@@ -58,12 +58,10 @@ private void RegisterHandlers(McpClientOptions options, NotificationHandlers not
     {
         McpClientHandlers handlers = options.Handlers;
 
-#pragma warning disable CS0618 // Type or member is obsolete
-        var notificationHandlersFromOptions = handlers.NotificationHandlers ?? options.Capabilities?.NotificationHandlers;
-        var samplingHandler = handlers.SamplingHandler ?? options.Capabilities?.Sampling?.SamplingHandler;
-        var rootsHandler = handlers.RootsHandler ?? options.Capabilities?.Roots?.RootsHandler;
-        var elicitationHandler = handlers.ElicitationHandler ?? options.Capabilities?.Elicitation?.ElicitationHandler;
-#pragma warning restore CS0618 // Type or member is obsolete
+        var notificationHandlersFromOptions = handlers.NotificationHandlers;
+        var samplingHandler = handlers.SamplingHandler;
+        var rootsHandler = handlers.RootsHandler;
+        var elicitationHandler = handlers.ElicitationHandler;
 
         if (notificationHandlersFromOptions is not null)
         {