SSR alert mail recipients maintainable in the site settings

New site setting vitec.ssr.alertEmails (Site Management, Settings, VITEC; one address per entry). vitec:ssr-health reads the recipients from there, invalid entries are skipped and logged, SSR_ALERT_EMAIL in the env file stays as fallback. The cockpit shows the recipients in the live band. Pre-filled with the address that was in the env file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/vitec/Classes/Controller/Backend/SsrController.php

@@ -70,6 +70,7 @@ final class SsrController
         $lastSample = $healthLog[0] ?? null;
         $clientErrors = $this->clientErrors(50);
         $cockpit = $this->cockpitData($health, $lastSample);
+        $alert = $this->purgeService->getAlertRecipients();
 
         $settingsUri = '';
         if ($GLOBALS['BE_USER']->isAdmin()) {
@@ -92,6 +93,10 @@ final class SsrController
             'cockpitJson' => json_encode($cockpit, JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT),
             'settingsUri' => $settingsUri,
             'failoverAfter' => $this->purgeService->getFailoverAfter(),
+            'alert' => $alert,
+            'alertList' => implode(', ', $alert['recipients']),
+            'alertCount' => count($alert['recipients']),
+            'alertInvalid' => implode(', ', $alert['invalid']),
             'chunkCount24h' => count(array_filter($clientErrors, static fn(array $r): bool => $r['is_chunk_reload'])),
             'jsErrorCount24h' => count(array_filter($clientErrors, static fn(array $r): bool => !$r['is_chunk_reload'])),
             'flagOn' => file_exists(Environment::getVarPath() . '/vitec-ssr-on.flag'),