feat: enums, schema and models for hado core

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BCrwHHnGCB5XH968Nxokqw

core/app/Enums/DueMode.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace App\Enums;
+
+enum DueMode: string
+{
+    case Local = 'local';
+    case Fixed = 'fixed';
+}