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/active-call-card.tsx

@@ -272,12 +272,12 @@ export const ActiveCallCard = ({ lead, callerPhone, missedCallId, onCallComplete
                     <div className="w-px h-6 bg-secondary mx-0.5" />
 
                     {/* Text+Icon primary actions */}
-                    <Button size="sm" color="secondary"
+                    <Button size="sm" color={appointmentOpen ? 'primary' : 'secondary'}
                         iconLeading={({ className, ...rest }: any) => <FontAwesomeIcon icon={faCalendarPlus} className={className} {...rest} />}
-                        onClick={() => setAppointmentOpen(true)}>Book Appt</Button>
-                    <Button size="sm" color="secondary"
+                        onClick={() => { setAppointmentOpen(!appointmentOpen); setEnquiryOpen(false); }}>Book Appt</Button>
+                    <Button size="sm" color={enquiryOpen ? 'primary' : 'secondary'}
                         iconLeading={({ className, ...rest }: any) => <FontAwesomeIcon icon={faClipboardQuestion} className={className} {...rest} />}
-                        onClick={() => setEnquiryOpen(!enquiryOpen)}>Enquiry</Button>
+                        onClick={() => { setEnquiryOpen(!enquiryOpen); setAppointmentOpen(false); }}>Enquiry</Button>
                     <Button size="sm" color="secondary"
                         iconLeading={({ className, ...rest }: any) => <FontAwesomeIcon icon={faPhoneArrowRight} className={className} {...rest} />}
                         onClick={() => setTransferOpen(!transferOpen)}>Transfer</Button>