Phase 0: Add booking permissions and constants

- Add AppointmentStatus enum (booked, cancelled_by_user, cancelled_by_admin)
- Add booking permissions for regular users (book_appointment, view_own_appointments, cancel_own_appointment)
- Add availability/appointments permissions for admin (manage_availability, view_all_appointments, cancel_any_appointment)
- Add booking constants to shared/constants.json (slotDurationMinutes, maxAdvanceDays, minAdvanceDays, noteMaxLength)
- Update validate_constants.py to validate new sections

backend/models.py

@@ -27,6 +27,16 @@ class Permission(str, PyEnum):
     # Invite permissions
     MANAGE_INVITES = "manage_invites"
     VIEW_OWN_INVITES = "view_own_invites"
+    
+    # Booking permissions (regular users)
+    BOOK_APPOINTMENT = "book_appointment"
+    VIEW_OWN_APPOINTMENTS = "view_own_appointments"
+    CANCEL_OWN_APPOINTMENT = "cancel_own_appointment"
+    
+    # Availability/Appointments permissions (admin)
+    MANAGE_AVAILABILITY = "manage_availability"
+    VIEW_ALL_APPOINTMENTS = "view_all_appointments"
+    CANCEL_ANY_APPOINTMENT = "cancel_any_appointment"
 
 
 class InviteStatus(str, PyEnum):
@@ -36,6 +46,13 @@ class InviteStatus(str, PyEnum):
     REVOKED = "revoked"
 
 
+class AppointmentStatus(str, PyEnum):
+    """Status of an appointment."""
+    BOOKED = "booked"
+    CANCELLED_BY_USER = "cancelled_by_user"
+    CANCELLED_BY_ADMIN = "cancelled_by_admin"
+
+
 # Role name constants
 ROLE_ADMIN = "admin"
 ROLE_REGULAR = "regular"
@@ -43,19 +60,25 @@ ROLE_REGULAR = "regular"
 # Role definitions with their permissions
 ROLE_DEFINITIONS: dict[str, RoleConfig] = {
     ROLE_ADMIN: {
-        "description": "Administrator with audit and invite management access",
+        "description": "Administrator with audit, invite, and appointment management access",
         "permissions": [
             Permission.VIEW_AUDIT,
             Permission.MANAGE_INVITES,
+            Permission.MANAGE_AVAILABILITY,
+            Permission.VIEW_ALL_APPOINTMENTS,
+            Permission.CANCEL_ANY_APPOINTMENT,
         ],
     },
     ROLE_REGULAR: {
-        "description": "Regular user with counter, sum, and invite access",
+        "description": "Regular user with counter, sum, invite, and booking access",
         "permissions": [
             Permission.VIEW_COUNTER,
             Permission.INCREMENT_COUNTER,
             Permission.USE_SUM,
             Permission.VIEW_OWN_INVITES,
+            Permission.BOOK_APPOINTMENT,
+            Permission.VIEW_OWN_APPOINTMENTS,
+            Permission.CANCEL_OWN_APPOINTMENT,
         ],
     },
 }