fix: use domain-based branding in check_auth response

check_auth was returning branding based on active company with
wrong field name (company_nimi instead of nimi), causing Noxus Intra
to show instead of company name on refresh. Now uses dbGetBranding()
with the request domain, same as the branding endpoint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api.php

@@ -845,20 +845,9 @@ switch ($action) {
             }
             // Hae allekirjoitukset
             $userSignatures = $u ? ($u['signatures'] ?? []) : [];
-            // Brändäystiedot aktiivisesta yrityksestä
-            $branding = ['primary_color' => '#0f3460', 'subtitle' => '', 'logo_url' => '', 'company_nimi' => ''];
-            $activeCompanyId = $_SESSION['company_id'] ?? '';
-            foreach ($allCompanies as $bc) {
-                if ($bc['id'] === $activeCompanyId) {
-                    $branding['primary_color'] = $bc['primary_color'] ?? '#0f3460';
-                    $branding['subtitle'] = $bc['subtitle'] ?? '';
-                    $branding['company_nimi'] = $bc['nimi'] ?? '';
-                    $branding['logo_url'] = !empty($bc['logo_file'])
-                        ? "api.php?action=company_logo&company_id=" . urlencode($bc['id'])
-                        : '';
-                    break;
-                }
-            }
+            // Brändäystiedot domain-pohjaisesti (sama kuin branding-endpoint)
+            $host = strtolower(explode(':', $_SERVER['HTTP_HOST'] ?? '')[0]);
+            $branding = dbGetBranding($host);
             echo json_encode([
                 'authenticated' => true,
                 'user_id' => $_SESSION['user_id'],