Fix: Update permission names, models and constants

Permission renames:
- BOOK_APPOINTMENT -> CREATE_EXCHANGE
- VIEW_OWN_APPOINTMENTS -> VIEW_OWN_EXCHANGES
- CANCEL_OWN_APPOINTMENT -> CANCEL_OWN_EXCHANGE
- VIEW_ALL_APPOINTMENTS -> VIEW_ALL_EXCHANGES
- CANCEL_ANY_APPOINTMENT -> CANCEL_ANY_EXCHANGE
- Add COMPLETE_EXCHANGE permission

Model changes:
- Delete AppointmentStatus enum
- Delete Appointment model

Schema changes:
- Delete BookingRequest (was for old booking)
- Delete AppointmentResponse, PaginatedAppointments
- Delete BookableSlot, AvailableSlotsResponse (unused)

Constants changes:
- Remove appointmentStatuses from shared/constants.json
- Merge booking constants into exchange section
- Update shared_constants.py and validate_constants.py

backend/models.py

@@ -41,15 +41,16 @@ class Permission(str, PyEnum):
     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"
+    # Exchange permissions (regular users)
+    CREATE_EXCHANGE = "create_exchange"
+    VIEW_OWN_EXCHANGES = "view_own_exchanges"
+    CANCEL_OWN_EXCHANGE = "cancel_own_exchange"
 
-    # Availability/Appointments permissions (admin)
+    # Availability/Exchange permissions (admin)
     MANAGE_AVAILABILITY = "manage_availability"
-    VIEW_ALL_APPOINTMENTS = "view_all_appointments"
-    CANCEL_ANY_APPOINTMENT = "cancel_any_appointment"
+    VIEW_ALL_EXCHANGES = "view_all_exchanges"
+    CANCEL_ANY_EXCHANGE = "cancel_any_exchange"
+    COMPLETE_EXCHANGE = "complete_exchange"
 
 
 class InviteStatus(str, PyEnum):
@@ -60,14 +61,6 @@ 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"
-
-
 class ExchangeStatus(str, PyEnum):
     """Status of an exchange trade."""
 
@@ -92,24 +85,25 @@ ROLE_REGULAR = "regular"
 # Role definitions with their permissions
 ROLE_DEFINITIONS: dict[str, RoleConfig] = {
     ROLE_ADMIN: {
-        "description": "Administrator with audit/invite/appointment access",
+        "description": "Administrator with audit/invite/exchange access",
         "permissions": [
             Permission.VIEW_AUDIT,
             Permission.FETCH_PRICE,
             Permission.MANAGE_INVITES,
             Permission.MANAGE_AVAILABILITY,
-            Permission.VIEW_ALL_APPOINTMENTS,
-            Permission.CANCEL_ANY_APPOINTMENT,
+            Permission.VIEW_ALL_EXCHANGES,
+            Permission.CANCEL_ANY_EXCHANGE,
+            Permission.COMPLETE_EXCHANGE,
         ],
     },
     ROLE_REGULAR: {
-        "description": "Regular user with profile, invite, and booking access",
+        "description": "Regular user with profile, invite, and exchange access",
         "permissions": [
             Permission.MANAGE_OWN_PROFILE,
             Permission.VIEW_OWN_INVITES,
-            Permission.BOOK_APPOINTMENT,
-            Permission.VIEW_OWN_APPOINTMENTS,
-            Permission.CANCEL_OWN_APPOINTMENT,
+            Permission.CREATE_EXCHANGE,
+            Permission.VIEW_OWN_EXCHANGES,
+            Permission.CANCEL_OWN_EXCHANGE,
         ],
     },
 }
@@ -303,33 +297,6 @@ class Availability(Base):
     )
 
 
-class Appointment(Base):
-    """User appointment bookings."""
-
-    __tablename__ = "appointments"
-    __table_args__ = (UniqueConstraint("slot_start", name="uq_appointment_slot_start"),)
-
-    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
-    user_id: Mapped[int] = mapped_column(
-        Integer, ForeignKey("users.id"), nullable=False, index=True
-    )
-    user: Mapped[User] = relationship("User", foreign_keys=[user_id], lazy="joined")
-    slot_start: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), nullable=False, index=True
-    )
-    slot_end: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
-    note: Mapped[str | None] = mapped_column(String(144), nullable=True)
-    status: Mapped[AppointmentStatus] = mapped_column(
-        Enum(AppointmentStatus), nullable=False, default=AppointmentStatus.BOOKED
-    )
-    created_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), default=lambda: datetime.now(UTC)
-    )
-    cancelled_at: Mapped[datetime | None] = mapped_column(
-        DateTime(timezone=True), nullable=True
-    )
-
-
 class PriceHistory(Base):
     """Price history records from external exchanges."""