feat: label AI-rescheduled appointments and add manual confirm option

- Add movedByAi boolean column to Appointment table (default false)
- reschedule-graph: set movedByAi=true when AI moves an appointment
- PATCH /api/appointments/:id/confirm endpoint clears the movedByAi flag
- Schedule grid: show teal AI badge on appointment cards where movedByAi=true
- Right-click context menu: 'Manually Confirmed' removes the AI badge via the confirm endpoint

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/db/prisma/schema.prisma

@@ -102,6 +102,7 @@ model Appointment {
   notes              String?
   procedureCodeNotes String?
   status             String   @default("scheduled") // "scheduled", "completed", "cancelled", "no-show"
+  movedByAi          Boolean  @default(false)
   createdAt          DateTime @default(now())
 
   eligibilityStatus PatientStatus @default(UNKNOWN)