fix(plan-correction): implement list_by_decision in CorrectionAttemptRepository

The domain protocol (CorrectionRepositoryProtocol.list_by_decision) was
added in the previous commit but the concrete SQLAlchemy-backed adapter
was missing this method, causing a run-time AttributeError whenever code
called the adapter.  This resolves the spec-compliance blocker from
PR review #7887 (issue #8531).

Changes:
- CorrectionAttemptRepository.list_by_decision(decision_id, *, new_only=False)
  queries CorrectionAttemptModel rows by original_decision_id with optional
  filtering on terminal states
- Follows the same @database_retry + session pattern as other repository methods
- Properly wraps DB errors in DatabaseError

ISSUES CLOSED: #8531

src/cleveragents/infrastructure/database/repositories.py

@@ -6056,6 +6056,50 @@ class CorrectionAttemptRepository:
                 f"Failed to list correction attempts for plan {plan_id}: {exc}"
             ) from exc
 
+    # --- LIST BY DECISION --------------------------------------------------
+
+    @database_retry
+    def list_by_decision(
+        self,
+        decision_id: str,
+        *,
+        new_only: bool = False,
+    ) -> list[CorrectionAttemptRecord]:
+        """List all correction attempts targeting a given decision.
+
+        Args:
+            decision_id: Decision ULID — the ``original_decision_id`` of
+                ``CorrectionAttemptModel`` rows to filter on.
+            new_only: If ``True``, only return corrections that have not yet
+                completed (i.e. state is neither ``"complete"`` nor
+                ``"failed"``). Defaults to ``False`` (returns all history).
+
+        Returns:
+            List of ``CorrectionAttemptRecord`` domain objects, ordered by
+            creation time ascending.
+
+        Raises:
+            DatabaseError: On transient or unexpected DB errors.
+        """
+        session = self._session()
+        try:
+            query = session.query(CorrectionAttemptModel).filter_by(
+                original_decision_id=decision_id,
+            )
+            if new_only:
+                query = query.filter(
+                    CorrectionAttemptModel.state.notin_(
+                        ("complete", "failed"),
+                    )
+                )
+            rows = query.order_by(CorrectionAttemptModel.created_at).all()
+            return [row.to_domain() for row in rows]
+        except (OperationalError, SQLAlchemyDatabaseError) as exc:
+            raise DatabaseError(
+                f"Failed to list correction attempts for decision "
+                f"{decision_id}: {exc}"
+            ) from exc
+
     # --- UPDATE STATE ------------------------------------------------------
 
     @database_retry