Embed event checkouts and send seller email to gateways.

Ticket/contribution payments open in a desktop modal or mobile sheet, initialize with the organizer email, and break out of the iframe after callback.

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

app/Services/Events/EventRegistrationService.php

@@ -130,11 +130,16 @@ class EventRegistrationService
             ? sprintf('%s — %s', $content['name'] ?? $qrCode->label, $tierName)
             : sprintf('%s ticket — %s', $content['name'] ?? $qrCode->label, $tierName);
 
+        $sellerEmail = trim((string) ($qrCode->user->email ?? ''));
+        if ($sellerEmail === '' || ! str_contains($sellerEmail, '@')) {
+            $sellerEmail = 'seller+'.($qrCode->user->public_id ?? 'events').'@checkout.ladill.local';
+        }
+
         $checkout = $this->gateway->initializeCheckout(
             $qrCode->user,
             $amountMinor,
             (string) ($registration->currency ?? 'GHS'),
-            $email,
+            $sellerEmail,
             LadillLink::path($qrCode->short_code, 'register/callback'),
             $registration->reference,
             [