feat: add absence notification and analytics features

- Implemented AbsenceNotifyView for notifying absence with session details.
- Created AnalyticsView for displaying group analytics and managing students at risk.
- Added ClassAttendanceView for marking attendance in classes.
- Defined new schemas for analytics and attendance in shared package.

apps/backend/src/modules/group-waitlist/lib/promote.ts

@@ -29,7 +29,9 @@ export async function promoteWaitlistEntryRecord(
   entry: GroupWaitlistEntryRecord,
 ): Promise<Result<AttendeeDto, ProblemDetails>> {
   if (group.capacity !== null) {
-    const currentCount = await db.attendee.count({ where: { groupId: group.id } });
+    const currentCount = await db.attendee.count({
+      where: { groupId: group.id, status: 'ACTIVE' },
+    });
     if (currentCount >= group.capacity) {
       return err(capacityReachedProblem(group.capacity));
     }