Add missing ConfigurationException and update PHPStan baseline (#31)

- Add ConfigurationException class in src/Exception/ConfigurationException.php
- Update ServerBuilder to use the new ConfigurationException
- Regenerate PHPStan baseline to account for the new exception class,
  reducing errors from 160+ to 124

Author: OskarStark

phpstan-baseline.neon

@@ -558,12 +558,6 @@ parameters:
 			count: 1
 			path: src/Server/RequestHandler/ListToolsHandler.php
 
-		-
-			message: '#^Instantiated class Mcp\\Server\\ConfigurationException not found\.$#'
-			identifier: class.notFound
-			count: 4
-			path: src/Server/ServerBuilder.php
-
 		-
 			message: '#^Method Mcp\\Server\\ServerBuilder\:\:getCompletionProviders\(\) return type has no value type specified in iterable type array\.$#'
 			identifier: missingType.iterableValue
@@ -701,9 +695,3 @@ parameters:
 			identifier: property.onlyWritten
 			count: 1
 			path: src/Server/ServerBuilder.php
-
-		-
-			message: '#^Throwing object of an unknown class Mcp\\Server\\ConfigurationException\.$#'
-			identifier: class.notFound
-			count: 4
-			path: src/Server/ServerBuilder.php

src/Exception/ConfigurationException.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\Exception;
+
+/**
+ * @author Oskar Stark <oskarstark@googlemail.com>
+ */
+class ConfigurationException extends InvalidArgumentException
+{
+}

src/Server/ServerBuilder.php

@@ -21,6 +21,7 @@
 use Mcp\Capability\Registry;
 use Mcp\Capability\Registry\Container;
 use Mcp\Capability\Registry\ReferenceHandler;
+use Mcp\Exception\ConfigurationException;
 use Mcp\JsonRpc\Handler;
 use Mcp\Schema\Annotations;
 use Mcp\Schema\Implementation;