feat(server): Rework transport architecture and add StreamableHttpTransport (#49)

* feat(server): Rework transport architecture and add StreamableHttpTransport

- `Server::connect()` no longer contains a processing loop.
- `TransportInterface` is updated with `setMessageHandler()` and `listen()`.
- `StdioTransport` is updated to implement the new interface.
- A new, minimal `StreamableHttpTransport` is added for stateless HTTP.

* refactor(server): use  event-driven message handling

* feat(server): Introduce a formal session management system

* fix: ensure session elements are preserved when building server (regression from #46)

* refactor: consolidate HTTP example to use shared dependencies

* feat(server): Enhance message handling with session support

- Updated `TransportInterface` to use `onMessage` for handling incoming messages with session IDs.
- Refactored `Server`, `Handler`, and transport classes to accommodate session management using `Uuid`.
- Introduced methods for creating sessions with auto-generated and specific UUIDs in `SessionFactory` and `SessionFactoryInterface`.

* feat(server): Integrate session management in message handling

- Added session support to the `Server` and `Handler` classes, allowing for session data to be managed during message processing.
- Updated `TransportInterface` to include session context in the `send` method.
- Refactored various request handlers to utilize session information, ensuring proper session handling for incoming requests.
- Introduced a file-based session store for persistent session data management

* feat: Update session builder method to use set* instead of with*

* feat: Fix test compatibility with new session management architecture

* chore: apply code style fixes

* fix: remove deprecated SSE transport and resolve PHPStan issues

examples/09-standalone-cli/index.php

@@ -11,6 +11,8 @@
 
 require __DIR__.'/vendor/autoload.php';
 
+use Mcp\Server;
+use Mcp\Server\Transport\StdioTransport;
 use Symfony\Component\Console as SymfonyConsole;
 use Symfony\Component\Console\Output\OutputInterface;
 
@@ -20,18 +22,14 @@ $debug = (bool) ($_SERVER['DEBUG'] ?? false);
 $output = new SymfonyConsole\Output\ConsoleOutput($debug ? OutputInterface::VERBOSITY_VERY_VERBOSE : OutputInterface::VERBOSITY_NORMAL);
 $logger = new SymfonyConsole\Logger\ConsoleLogger($output);
 
-// Configure the JsonRpcHandler and build the functionality
-$jsonRpcHandler = new Mcp\JsonRpc\Handler(
-    Mcp\JsonRpc\MessageFactory::make(),
-    App\Builder::buildMethodHandlers(),
-    $logger
-);
+$server = Server::make()
+    ->setServerInfo('Standalone CLI', '1.0.0')
+    ->setLogger($logger)
+    ->setDiscovery(__DIR__, ['.'])
+    ->build();
 
-// Set up the server
-$sever = new Mcp\Server($jsonRpcHandler, $logger);
+$transport = new StdioTransport(logger: $logger);
 
-// Create the transport layer using Stdio
-$transport = new Mcp\Server\Transport\StdioTransport(logger: $logger);
+$server->connect($transport);
 
-// Start our application
-$sever->connect($transport);
+$transport->listen();