feat: redesign day picker with expandable calendar, status markers & Playwright E2E testing

- Replace modal calendar with inline expandable calendar widget integrated into the day picker.
- Add status indicator dots (attended/absent/pending) to month calendar grid matching day picker.
- Disable and gray out weekend days in calendar when weekend schedule is turned off.
- Redesign extend bar with integrated handle that aligns with the palette.
- Remove start-to-end timing on Today screen's class time rail, showing only start time.
- Implement Playwright E2E and visual testing suite with multi-screen capture scripts.
- Add cascade DELETE endpoints for subjects and versioned recurring timetable entries.

lib/api.ts

@@ -25,12 +25,15 @@ export const collegeApi = {
   createSubject(data: { name: string; code: string; shortName?: string; color?: string; classType?: string; defaultRoom?: string }) { return request<{ id: number }>('/subjects', { method: 'POST', body: JSON.stringify(data) }); },
   subject(id: number) { return request<{ id: number; name: string; code: string; shortName: string; color: string; classType: string; defaultRoom: string; summary: { total: number; attended: number; absent: number; percentage: number }; sessions: Array<{ id: number; date: string; time: string; endTime: string; room: string; status: AttendanceStatus }> }>(`/subjects/${id}`); },
   updateSubject(id: number, data: { name: string; code: string; shortName: string; color?: string; classType?: string; defaultRoom?: string }) { return request<{ id: number }>(`/subjects/${id}`, { method: 'PATCH', body: JSON.stringify(data) }); },
+  deleteSubject(id: number) { return request<{ id: number; deleted: boolean }>(`/subjects/${id}`, { method: 'DELETE' }); },
   schedule(date: string) { return request<{ date: string; sessions: Session[] }>(`/schedule?date=${date}`); },
   markAttendance(id: number, status: AttendanceStatus) { return request<{ id: number; status: AttendanceStatus }>(`/schedule/${id}/attendance`, { method: 'PUT', body: JSON.stringify({ status }) }); },
   removeClass(id: number) { return request<{ id: number; deleted: boolean }>(`/schedule/${id}`, { method: 'DELETE' }); },
   addOneOffClass(data: { subjectId: number; date: string; startTime: string; endTime: string; room: string }) { return request<{ id: number }>('/schedule', { method: 'POST', body: JSON.stringify(data) }); },
   attendanceSummary() { return request<{ subjects: Array<{ id: number; name: string; code: string; shortName?: string; color: string; total: number; attended: number; absent: number; cancelled: number; percentage: number }> }>('/attendance/summary'); },
+  attendanceMarkers(month: string) { return request<{ markers: Record<string, 'success' | 'warning' | 'danger' | 'neutral'> }>(`/attendance/markers?month=${month}`); },
   timetable(date: string) { return request<{ date: string; classes: Array<{ id: number; weekday: number; startTime: string; endTime: string; room: string; subjectId: number; subjectName: string; code: string; color: string; classType: string; effectiveFrom: string; effectiveTo: string | null }> }>(`/timetable/classes?date=${date}`); },
   updateTimetableClass(id: number, data: { subjectId?: number; weekday?: number; startTime?: string; endTime?: string; room?: string; effectiveFrom?: string }) { return request<{ id: number; replacesId: number; effectiveFrom: string }>(`/timetable/classes/${id}`, { method: 'PATCH', body: JSON.stringify(data) }); },
+  deleteTimetableClass(id: number) { return request<{ id: number; deleted: boolean }>(`/timetable/classes/${id}`, { method: 'DELETE' }); },
   addTimetableClass(data: { subjectId: number; weekday: number; startTime: string; endTime: string; room: string; effectiveFrom?: string }) { return request<{ id: number }>('/timetable/classes', { method: 'POST', body: JSON.stringify(data) }); },
 };