Add Ladill POS v1 — register, Pay checkout, and commerce links.

Staff-facing counter register at pos.ladill.com with catalog cart, cash and
MoMo/card checkout via Ladill Pay, CRM timeline/import, invoice prefill, and
Merchant catalog import.

Co-authored-by: Cursor <cursoragent@cursor.com>

config/identity.php

@@ -0,0 +1,6 @@
+<?php
+
+return [
+    'api_url' => env('IDENTITY_API_URL', 'https://ladill.com/api'),
+    'api_key' => env('IDENTITY_API_KEY_MINI'),
+];