fix: UUID type mismatch, slot conflict, appt/enquiry tabs, dialler in header

- Changed $id: ID! to $id: UUID! in all update mutations (4 files)
- Removed redundant slot availability check (UI already disables booked slots)
- Book Appt and Enquiry act as toggle tabs — one closes the other
- Dialler moved from FAB to header dropdown next to status toggle

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

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

@@ -208,7 +208,7 @@ export const AppointmentForm = ({
             if (isEditMode && existingAppointment) {
                 // Update existing appointment
                 await apiClient.graphql(
-                    `mutation UpdateAppointment($id: ID!, $data: AppointmentUpdateInput!) {
+                    `mutation UpdateAppointment($id: UUID!, $data: AppointmentUpdateInput!) {
                         updateAppointment(id: $id, data: $data) { id }
                     }`,
                     {
@@ -224,22 +224,6 @@ export const AppointmentForm = ({
                 );
                 notify.success('Appointment Updated');
             } else {
-                // Double-check slot availability before booking
-                const checkResult = await apiClient.graphql<{ appointments: { edges: Array<{ node: { status: string } }> } }>(
-                    `{ appointments(filter: {
-                        doctorId: { eq: "${doctor}" },
-                        scheduledAt: { gte: "${date}T${timeSlot}:00", lte: "${date}T${timeSlot}:00" }
-                    }) { edges { node { status } } } }`,
-                );
-                const activeBookings = checkResult.appointments.edges.filter(e =>
-                    e.node.status !== 'CANCELLED' && e.node.status !== 'NO_SHOW',
-                );
-                if (activeBookings.length > 0) {
-                    setError('This slot was just booked by someone else. Please select a different time.');
-                    setIsSaving(false);
-                    return;
-                }
-
                 // Create appointment
                 await apiClient.graphql(
                     `mutation CreateAppointment($data: AppointmentCreateInput!) {
@@ -263,7 +247,7 @@ export const AppointmentForm = ({
                 // Update lead status if we have a matched lead
                 if (leadId) {
                     await apiClient.graphql(
-                        `mutation UpdateLead($id: ID!, $data: LeadUpdateInput!) {
+                        `mutation UpdateLead($id: UUID!, $data: LeadUpdateInput!) {
                             updateLead(id: $id, data: $data) { id }
                         }`,
                         {
@@ -291,7 +275,7 @@ export const AppointmentForm = ({
         setIsSaving(true);
         try {
             await apiClient.graphql(
-                `mutation CancelAppointment($id: ID!, $data: AppointmentUpdateInput!) {
+                `mutation CancelAppointment($id: UUID!, $data: AppointmentUpdateInput!) {
                     updateAppointment(id: $id, data: $data) { id }
                 }`,
                 {