feat: add Plugins module with base files for plugins architecture

modules/Plugins/PluginInterface.php

@@ -0,0 +1,16 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Modules\Plugins;
+
+use App\Entities\Episode;
+use App\Entities\Podcast;
+use App\Libraries\SimpleRSSElement;
+
+interface PluginInterface
+{
+    public function setChannelTag(Podcast $podcast, SimpleRSSElement $channel): void;
+
+    public function setItemTag(Episode $episode, SimpleRSSElement $item): void;
+}