Notify transfer owners when files enter grace period.

Send grace-entered and countdown emails to owners alongside recipient grace milestones so unpaid transfers get clear wallet top-up reminders before deletion.

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

app/Models/User.php

@@ -87,4 +87,12 @@ class User extends Authenticatable
 
         return $url !== '' ? $url : null;
     }
+
+    /** @return array<int, string>|string */
+    public function routeNotificationForMail(mixed $notification): array|string
+    {
+        $notifyEmail = trim((string) ($this->qrSetting?->notify_email ?? ''));
+
+        return $notifyEmail !== '' ? $notifyEmail : (string) $this->email;
+    }
 }