Add new ScheduleTab to main navigation with ScheduleStackNavigator for managing course schedule screens. Includes CourseDetailScreen with modal presentation. Also exports scheduleService and related types for the new schedule feature.
fix(message): add group_id parameter to invite and request handlers
Pass group_id from extra_data when calling respondInvite and reviewJoinRequest APIs, as the backend now requires this parameter.
refactor(message): extract mergeMessagesById helper method
Centralize message merging logic into a reusable private method to avoid duplication and ensure consistent message deduplication behavior.
