feat : add RecurrenceType backed enum

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/Enum/RecurrenceType.php

@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Enum;
+
+enum RecurrenceType: string
+{
+    case Daily   = 'daily';
+    case Weekly  = 'weekly';
+    case Monthly = 'monthly';
+    case Yearly  = 'yearly';
+}