feat: add board goals, memory, approvals, onboarding models

backend/app/models/task_fingerprints.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from datetime import datetime
+from uuid import UUID, uuid4
+
+from sqlmodel import Field, SQLModel
+
+
+class TaskFingerprint(SQLModel, table=True):
+    __tablename__ = "task_fingerprints"
+
+    id: UUID = Field(default_factory=uuid4, primary_key=True)
+    board_id: UUID = Field(foreign_key="boards.id", index=True)
+    fingerprint_hash: str = Field(index=True)
+    task_id: UUID = Field(foreign_key="tasks.id")
+    created_at: datetime = Field(default_factory=datetime.utcnow)