feat: worklist sorting, contextual disposition, context panel redesign, notifications

- Worklist default sort descending (newest first), sortable column headers (PRIORITY, PATIENT, SLA) via React Aria
- Contextual disposition: auto-selects based on in-call actions (appointment → APPOINTMENT_BOOKED, enquiry → INFO_PROVIDED, transfer → FOLLOW_UP_SCHEDULED)
- Context panel redesign: collapsible AI Insight, Upcoming (appointments + follow-ups + linked patient), Recent (calls + activities) sections; auto-collapse on AI chat start
- Appointments added to DataProvider with APPOINTMENTS_QUERY, Appointment type, transform
- Notification bell for admin/supervisor: performance alerts (idle time, NPS, conversion thresholds) with toast on load + bell dropdown with dismiss; demo alerts as fallback
- Slideout z-index fix: added z-50 to slideout ModalOverlay matching modal component

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/call-desk/appointment-form.tsx

@@ -198,6 +198,12 @@ export const AppointmentForm = ({
             return;
         }
 
+        const today = new Date().toISOString().split('T')[0];
+        if (!isEditMode && date < today) {
+            setError('Appointment date cannot be in the past.');
+            return;
+        }
+
         setIsSaving(true);
         setError(null);