Get actor_id from pending_runs when saving completed run

When a DAG task completes, look up actor_id from pending_runs
(where it was saved when the run started) and include it in
run_cache. Also clean up pending_runs entry after completion.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

legacy_tasks.py

@@ -383,13 +383,23 @@ def execute_dag(self, dag_json: str, run_id: str = None) -> dict:
                     if (node.node_type == NodeType.SOURCE or str(node.node_type) == "SOURCE")
                     and node.config.get("content_hash")
                 ]
+                # Get actor_id from pending_runs (saved when run started)
+                actor_id = None
+                pending = await database.get_pending_run(run_id)
+                if pending:
+                    actor_id = pending.get("actor_id")
+
                 await database.save_run_cache(
                     run_id=run_id,
                     output_hash=output_hash,
                     recipe="dag",
                     inputs=input_hashes_for_db,
                     ipfs_cid=output_ipfs_cid,
+                    actor_id=actor_id,
                 )
+                # Clean up pending run
+                if pending:
+                    await database.complete_pending_run(run_id)
 
         try:
             loop = asyncio.get_event_loop()