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

tests/JsonRpc/HandlerTest.php

@@ -15,8 +15,12 @@ use Mcp\JsonRpc\Handler;
 use Mcp\JsonRpc\MessageFactory;
 use Mcp\Schema\JsonRpc\Response;
 use Mcp\Server\MethodHandlerInterface;
+use Mcp\Server\Session\SessionFactoryInterface;
+use Mcp\Server\Session\SessionInterface;
+use Mcp\Server\Session\SessionStoreInterface;
 use PHPUnit\Framework\Attributes\TestDox;
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Uid\Uuid;
 
 class HandlerTest extends TestCase
 {
@@ -44,9 +48,24 @@ class HandlerTest extends TestCase
         $handlerC->method('supports')->willReturn(true);
         $handlerC->expects($this->once())->method('handle');
 
-        $jsonRpc = new Handler(MessageFactory::make(), [$handlerA, $handlerB, $handlerC]);
+        $sessionFactory = $this->createMock(SessionFactoryInterface::class);
+        $sessionStore = $this->createMock(SessionStoreInterface::class);
+        $session = $this->createMock(SessionInterface::class);
+
+        $sessionFactory->method('create')->willReturn($session);
+        $sessionFactory->method('createWithId')->willReturn($session);
+        $sessionStore->method('exists')->willReturn(true);
+
+        $jsonRpc = new Handler(
+            MessageFactory::make(),
+            $sessionFactory,
+            $sessionStore,
+            [$handlerA, $handlerB, $handlerC]
+        );
+        $sessionId = Uuid::v4();
         $result = $jsonRpc->process(
-            '{"jsonrpc": "2.0", "method": "notifications/initialized"}'
+            '{"jsonrpc": "2.0", "method": "notifications/initialized"}',
+            $sessionId
         );
         iterator_to_array($result);
     }
@@ -75,9 +94,24 @@ class HandlerTest extends TestCase
         $handlerC->method('supports')->willReturn(true);
         $handlerC->expects($this->never())->method('handle');
 
-        $jsonRpc = new Handler(MessageFactory::make(), [$handlerA, $handlerB, $handlerC]);
+        $sessionFactory = $this->createMock(SessionFactoryInterface::class);
+        $sessionStore = $this->createMock(SessionStoreInterface::class);
+        $session = $this->createMock(SessionInterface::class);
+
+        $sessionFactory->method('create')->willReturn($session);
+        $sessionFactory->method('createWithId')->willReturn($session);
+        $sessionStore->method('exists')->willReturn(true);
+
+        $jsonRpc = new Handler(
+            MessageFactory::make(),
+            $sessionFactory,
+            $sessionStore,
+            [$handlerA, $handlerB, $handlerC]
+        );
+        $sessionId = Uuid::v4();
         $result = $jsonRpc->process(
-            '{"jsonrpc": "2.0", "id": 1, "method": "tools/list"}'
+            '{"jsonrpc": "2.0", "id": 1, "method": "tools/list"}',
+            $sessionId
         );
         iterator_to_array($result);
     }