feat: implement download

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

lib/Client/Transport/ConnectionInterface.php

@@ -20,5 +20,13 @@ interface ConnectionInterface
 
     public function readBytes(int $length): string;
 
+    /**
+     * Yield the literal payload in chunks without buffering the full content.
+     * Reads exactly $length bytes from the socket, never crossing the literal boundary.
+     *
+     * @return \Generator<string>
+     */
+    public function readBytesChunked(int $length, int $chunkSize = 8192): \Generator;
+
     public function upgradeToTls(): void;
 }