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/PosSale.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+
+class PosSale extends Model
+{
+    public const STATUS_PENDING = 'pending';
+
+    public const STATUS_PAID = 'paid';
+
+    public const STATUS_FAILED = 'failed';
+
+    public const STATUS_CANCELLED = 'cancelled';
+
+    public const METHOD_PAY = 'pay';
+
+    public const METHOD_CASH = 'cash';
+
+    protected $fillable = [
+        'owner_ref',
+        'location_id',
+        'reference',
+        'status',
+        'payment_method',
+        'pay_order_id',
+        'payment_reference',
+        'customer_name',
+        'customer_email',
+        'customer_phone',
+        'crm_customer_id',
+        'subtotal_minor',
+        'total_minor',
+        'currency',
+        'paid_at',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'subtotal_minor' => 'integer',
+            'total_minor' => 'integer',
+            'pay_order_id' => 'integer',
+            'crm_customer_id' => 'integer',
+            'paid_at' => 'datetime',
+        ];
+    }
+
+    public function location(): BelongsTo
+    {
+        return $this->belongsTo(PosLocation::class, 'location_id');
+    }
+
+    public function lines(): HasMany
+    {
+        return $this->hasMany(PosSaleLine::class)->orderBy('position');
+    }
+
+    public function isPaid(): bool
+    {
+        return $this->status === self::STATUS_PAID;
+    }
+
+    public function scopeOwned(Builder $query, string $ownerRef): Builder
+    {
+        return $query->where('owner_ref', $ownerRef);
+    }
+}