Handle Ombi API object-format requestedUser field

The Ombi API returns requestedUser as an OmbiUser object instead of a string.
Add extractRequestedUser helper to extract username from various fields
(alias, userAlias, userName, normalizedUserName) with fallback to legacy string format.
Update client and server routes to use the helper for consistent username extraction.

server/routes/webhook.js

@@ -6,6 +6,7 @@ const { getWebhookSecret, getSonarrInstances, getRadarrInstances, getOmbiInstanc
 const cache = require('../utils/cache');
 const arrRetrieverRegistry = require('../utils/arrRetrievers');
 const { pollAllServices, POLL_INTERVAL, POLLING_ENABLED } = require('../utils/poller');
+const { extractRequestedUser } = require('../utils/ombiHelpers');
 
 const router = express.Router();
 
@@ -661,6 +662,9 @@ router.post('/ombi', webhookLimiter, (req, res) => {
   // Ombi uses notificationType instead of eventType
   const { notificationType, requestId, requestedUser, applicationUrl } = req.body;
   const eventType = notificationType || req.body.eventType;
+  
+  // Extract username from requestedUser (handles both object and string formats)
+  const username = extractRequestedUser(req.body);
 
   if (!eventType || !OMBI_EVENTS.has(eventType)) {
     logToFile(`[Webhook] Ombi payload rejected: invalid or missing notificationType`);
@@ -678,7 +682,7 @@ router.post('/ombi', webhookLimiter, (req, res) => {
   }
 
   try {
-    logToFile(`[Webhook] Ombi event received - Type: ${eventType}, RequestId: ${requestId}, User: ${requestedUser}`);
+    logToFile(`[Webhook] Ombi event received - Type: ${eventType}, RequestId: ${requestId}, User: ${username}`);
     logToFile(`[Webhook] Ombi payload: ${JSON.stringify(req.body)}`);
 
     // Update webhook metrics for polling optimization