feat(tasks): define investigation report contract and history

app/infra/db/postgresql/operational_tasks.py

@@ -409,6 +409,24 @@ class OperationalTaskRepository:
     async def get_latest_report(self, task_id: str) -> dict | None:
         return await self._latest_artifact("operational_task_reports", task_id)
 
+    async def get_report(self, task_id: str, revision: int) -> dict | None:
+        cursor = await self.connection.execute(
+            """SELECT document FROM workbench.operational_task_reports
+               WHERE project_id=%s AND task_id=%s AND revision=%s""",
+            (self.project_id, task_id, revision),
+        )
+        row = await cursor.fetchone()
+        return row["document"] if row else None
+
+    async def list_reports(self, task_id: str, limit: int, offset: int) -> list[dict]:
+        cursor = await self.connection.execute(
+            """SELECT document FROM workbench.operational_task_reports
+               WHERE project_id=%s AND task_id=%s ORDER BY revision DESC
+               LIMIT %s OFFSET %s""",
+            (self.project_id, task_id, limit, offset),
+        )
+        return [row["document"] for row in await cursor.fetchall()]
+
     async def _latest_artifact(self, table: str, task_id: str) -> dict | None:
         if table not in {"operational_task_plans", "operational_task_reports"}:
             raise ValueError("unsupported artifact table")
@@ -535,7 +553,7 @@ class OperationalTaskRepository:
                SET document=document || jsonb_build_object(
                    'lifecycle_status','resolved',
                    'resolved_at',to_jsonb(%s::timestamptz),
-                   'resolution_reason',%s
+                   'resolution_reason',%s::text
                )
                WHERE project_id=%s AND task_id=%s
                  AND COALESCE(document->>'lifecycle_status','active')='active'