feat(billing): renewals, coupons, VAT numbering, billing cycles and invoice payment tracking

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/Support/CustomerBillingProfile.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Support;
+
+use App\Models\Customer;
+
+class CustomerBillingProfile
+{
+    public const FIELDS = ['invoice_company', 'tax_code', 'invoice_address', 'invoice_email'];
+
+    public static function payload(Customer $customer): array
+    {
+        return [
+            'invoice_company' => $customer->invoice_company,
+            'tax_code' => $customer->tax_code,
+            'invoice_address' => $customer->invoice_address,
+            'invoice_email' => $customer->invoice_email,
+        ];
+    }
+
+    public static function save(Customer $customer, array $input): array
+    {
+        $customer->update(array_map(
+            fn ($value) => is_string($value) && trim($value) === '' ? null : $value,
+            array_intersect_key($input, array_flip(self::FIELDS)) + array_fill_keys(self::FIELDS, null),
+        ));
+
+        return self::payload($customer->fresh());
+    }
+}