Make guest landing-page checkouts email-optional like Ladill Mini.

Drop required buyer email on public merchant forms; require phone for bookings so merchants can reach guests without Ladill accounts.

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

app/Services/Merchant/GiveDonationService.php

@@ -56,7 +56,7 @@ class MerchantSaleService
             'amount_minor' => $amountMinor,
             'currency' => $qrCode->content()['currency'] ?? 'GHS',
             'payer_name' => trim((string) ($data['customer_name'] ?? '')),
-            'payer_email' => trim((string) ($data['customer_email'] ?? '')),
+            'payer_email' => ($email = trim((string) ($data['customer_email'] ?? ''))) !== '' ? $email : null,
             'payer_phone' => trim((string) ($data['customer_phone'] ?? '')),
             'status' => QrSaleOrder::STATUS_PENDING,
             'payment_reference' => null,