fix(settings): read SuperAdmin overlay via ConfigService everywhere

app/Services/SmsBilling/SmsWalletService.php

@@ -6,6 +6,7 @@ use App\Models\Setting;
 use App\Models\SmsLedger;
 use App\Models\SmsSendLog;
 use App\Models\SmsWallet;
+use App\Services\ConfigService;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Schema;
 
@@ -36,7 +37,7 @@ class SmsWalletService
     /** Billing/panel فعال است مگر sms_panel صریحاً false باشد. */
     public static function isBillingEnabled(): bool
     {
-        $value = Setting::where('key', 'sms_panel')->value('value');
+        $value = app(ConfigService::class)->getString('sms_panel');
 
         if ($value === null || trim((string) $value) === '') {
             return true;