Enable servers to send sampling messages to clients (#101)

src/Schema/Enum/SamplingContext.php

@@ -0,0 +1,19 @@
+<?php
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Mcp\Schema\Enum;
+
+enum SamplingContext: string
+{
+    case NONE = 'none';
+    case THIS_SERVER = 'thisServer';
+    case ALL_SERVERS = 'allServers';
+}