refactor(horizon): use config for allowed emails and update gate definition

Author: maartenbode

app/Providers/HorizonServiceProvider.php

@@ -30,7 +30,7 @@ protected function gate(): void
         Gate::define('viewHorizon', static function (User $user) {
             return in_array(
                 needle: $user->email,
-                haystack: explode(',', env('HORIZON_ALLOWED_EMAILS')),
+                haystack: explode(',', (string) config('horizon.allowed_emails')),
                 strict: true
             );
         });

config/horizon.php

@@ -4,6 +4,18 @@
 
 return [
 
+    /*
+    |--------------------------------------------------------------------------
+    | Allowed Emails
+    |--------------------------------------------------------------------------
+    |
+    | A comma-separated list of email addresses that are allowed to access
+    | the Horizon dashboard in non-local environments.
+    |
+    */
+
+    'allowed_emails' => env('HORIZON_ALLOWED_EMAILS', ''),
+
     /*
     |--------------------------------------------------------------------------
     | Horizon Name