feat(call): implement group calling and enhance call management

Introduces group calling capabilities, including group invites and participant
lifecycle management. Enhances the existing call system with support for
media types (voice/video) and improved participant tracking.

- Add `GroupInvite` and `ParticipantJoin/Leave` to `CallService`.
- Implement WebSocket handlers for `call_group_invite` and
  `call_participant_join`.
- Update `CallSession` model to support group IDs, media types, and
  tracking who ended the call.
- Integrate `GroupService` into `CallService` via dependency injection.
- Add error constants for group call limitations and participant capacity.
- Update LiveKit webhook handling to process participant leave events.

Refactor grade synchronization to remove semester-based filtering in favor
of a more flexible user-based approach and improve GPA summary updates.

cmd/server/wire_gen.go

@@ -137,7 +137,7 @@ func InitializeApp() (*App, error) {
 	materialService := wire.ProvideMaterialService(materialSubjectRepository, materialFileRepository)
 	materialHandler := handler.NewMaterialHandler(materialService)
 	callRepository := repository.NewCallRepository(db)
-	callService := wire.ProvideCallService(callRepository, messagePublisher, config, db, client)
+	callService := wire.ProvideCallService(callRepository, messagePublisher, config, db, client, groupService)
 	callHandler := handler.NewCallHandler(callService)
 	reportRepository := repository.NewReportRepository(db)
 	reportService := wire.ProvideReportService(reportRepository, postRepository, commentRepository, messageRepository, userRepository, systemNotificationRepository, pushService, transactionManager, operationLogService, config)