fix: correct participant data mapping in event chat sidebar

- Fix participant data structure mapping (use p.userId instead of p.user.id)
- Backend returns flat participant objects, not nested user objects
- Remove debug console.log statements
- Participants list now correctly displays all checked-in users

frontend/src/pages/EventChatPage.jsx

@@ -90,11 +90,11 @@ const EventChatPage = () => {
         if (eventDetails.data && eventDetails.data.participants) {
           const participants = eventDetails.data.participants
             .map(p => ({
-              userId: p.user.id,
-              username: p.user.username,
-              avatar: p.user.avatar || `https://api.dicebear.com/7.x/avataaars/svg?seed=${p.user.username}`,
-              firstName: p.user.firstName,
-              lastName: p.user.lastName,
+              userId: p.userId,
+              username: p.username,
+              avatar: p.avatar || `https://api.dicebear.com/7.x/avataaars/svg?seed=${p.username}`,
+              firstName: p.firstName,
+              lastName: p.lastName,
             }))
             .filter(p => p.userId !== user.id); // Exclude current user
           setCheckedInUsers(participants);