Add dispute system

backend/app/models/__init__.py

@@ -7,6 +7,7 @@ from app.models.assignment import Assignment, AssignmentStatus
 from app.models.activity import Activity, ActivityType
 from app.models.event import Event, EventType
 from app.models.swap_request import SwapRequest, SwapRequestStatus
+from app.models.dispute import Dispute, DisputeStatus, DisputeComment, DisputeVote
 
 __all__ = [
     "User",
@@ -30,4 +31,8 @@ __all__ = [
     "EventType",
     "SwapRequest",
     "SwapRequestStatus",
+    "Dispute",
+    "DisputeStatus",
+    "DisputeComment",
+    "DisputeVote",
 ]