refactor: Clean up cron initialization logs

Single summary line instead of verbose duplicates:
[INFO] Cron jobs initialized: Calendar (07:00), Audit cleanup (00:00)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cron/index.js

@@ -6,15 +6,18 @@ import { startAuditCleanupCron, cleanupOldAuditLogs } from './cleanupAuditLogs.j
  * Start all cron jobs
  */
 export const startAllCronJobs = () => {
-  logger.info('=== Inicializujem cron jobs ===');
+  const jobs = [];
 
   // Calendar event notifications
-  startCalendarNotificationCron();
+  const calendarJob = startCalendarNotificationCron();
+  jobs.push(calendarJob);
 
-  // Audit logs cleanup (daily at midnight)
-  startAuditCleanupCron();
+  // Audit logs cleanup
+  const auditJob = startAuditCleanupCron();
+  jobs.push(auditJob);
 
-  logger.info('=== Všetky cron jobs inicializované ===');
+  // Log summary
+  logger.info(`Cron jobs initialized: ${jobs.map(j => j.name).join(', ')}`);
 };
 
 // Export individual functions for testing/manual triggers