Implemented subscription logic

src/Broker/SseSubscriber.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace NoccyLabs\Mercureact\Broker;
+
+use React\Stream\WritableStreamInterface;
+
+class SseSubscriber implements SubscriberInterface
+{
+    public function __construct(
+        private WritableStreamInterface $stream
+    )
+    {
+    }
+
+    public function deliver(Message $message): void
+    {
+        $this->stream->write($message->toString());
+    }
+
+    public function isAuthorized(string $topics): bool
+    {
+        return true;
+    }
+}