Retire Events subscriptions and owner payment gateways.

Make Ladill Events free for all accounts, remove plan upgrade UI, force Ladill Pay only for tickets and contributions, and reinstate standard platform fees.

app/Services/Payments/MerchantGatewayService.php

@@ -24,8 +24,9 @@ class MerchantGatewayService
 
     public function shouldUseOwnerGateway(User|string $owner): bool
     {
-        return $this->ownerMayUseGateway($owner)
-            && (bool) $this->settingFor($owner)?->isConfigured();
+        // Custom / owner payment gateways are retired. All checkouts use Ladill Pay
+        // with platform fees.
+        return false;
     }
 
     /**
@@ -88,15 +89,7 @@ class MerchantGatewayService
 
     protected function ownerMayUseGateway(User|string $owner): bool
     {
-        $user = $owner instanceof User
-            ? $owner
-            : User::query()->where('public_id', (string) $owner)->first();
-
-        if (! $user) {
-            return false;
-        }
-
-        return app(SubscriptionService::class)->canUsePaymentGateway($user);
+        return false;
     }
 
     /**