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>

app/Models/PosProduct.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class PosProduct extends Model
+{
+    protected $fillable = [
+        'owner_ref',
+        'location_id',
+        'name',
+        'sku',
+        'price_minor',
+        'currency',
+        'is_active',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'price_minor' => 'integer',
+            'is_active' => 'boolean',
+        ];
+    }
+
+    public function location(): BelongsTo
+    {
+        return $this->belongsTo(PosLocation::class, 'location_id');
+    }
+
+    public function scopeOwned(Builder $query, string $ownerRef): Builder
+    {
+        return $query->where('owner_ref', $ownerRef);
+    }
+
+    public function scopeActive(Builder $query): Builder
+    {
+        return $query->where('is_active', true);
+    }
+}