feat(purchase): implement PurchaseController with CRUD operations and request validation

app/Domains/Purchase/Resources/PurchaseResource.php

@@ -0,0 +1,49 @@
+<?php
+
+namespace App\Domains\Purchase\Resources;
+
+use Illuminate\Http\Request;
+use Illuminate\Http\Resources\Json\JsonResource;
+
+/**
+ * @mixin \App\Domains\Purchase\Models\Purchase
+ */
+class PurchaseResource extends JsonResource
+{
+    /**
+     * @return array<string, mixed>
+     */
+    public function toArray(Request $request): array
+    {
+        $items = $this->resource->relationLoaded('items')
+            ? $this->resource->getRelation('items')
+            : collect();
+
+        $subtotal = $items->reduce(
+            fn (float $carry, $item): float => $carry + ((float) $item->precio_unitario * $item->cantidad),
+            0.0,
+        );
+
+        $total = $items->reduce(
+            fn (float $carry, $item): float => $carry + (float) $item->total,
+            0.0,
+        );
+
+        return [
+            'id' => $this->id,
+            'tenant_codigo' => $this->tenant_codigo,
+            'user_id' => $this->user_id,
+            'status' => $this->status,
+            'payment_status' => $this->payment_status,
+            'payment_method' => $this->payment_method,
+            'items' => PurchaseItemResource::collection($items),
+            'subtotal' => $this->formatMoney($subtotal),
+            'total' => $this->formatMoney($total),
+        ];
+    }
+
+    protected function formatMoney(float|int|string|null $amount): string
+    {
+        return number_format((float) ($amount ?? 0), 2, '.', '');
+    }
+}