feat(frontend): add recording matching UI

Add frontend components for auto-matching recording partners:

- RecordingTab component with suggestions list and opt-out toggle
- Tab navigation in EventChatPage (Chat, Uczestnicy, Nagrywanie)
- Matching configuration in EventDetailsPage (deadline, run matching)
- matchingAPI functions in api.js
- Return registrationDeadline and matchingRunAt in GET /events/:slug/details

UI allows users to:
- View who will record their heats
- View heats they need to record
- Accept/reject suggestions
- Opt-out from being a recorder
- Set registration deadline (admin)
- Manually trigger matching (admin)

backend/src/routes/events.js

@@ -379,6 +379,8 @@ router.get('/:slug/details', authenticate, async (req, res, next) => {
           startDate: event.startDate,
           endDate: event.endDate,
           description: event.description,
+          registrationDeadline: event.registrationDeadline,
+          matchingRunAt: event.matchingRunAt,
         },
         checkin: {
           token: checkinToken.token,