#471 Performance: Unnecessary list() around dict.keys() in multiple files

Several files wrap dict.keys() in list() unnecessarily for iteration: 1. engine/tools/parallel_join.py:44 - branch_names = list(fork_task_result['spawned_tasks'].keys()) 2. engine/tools/docker/compose.py:388 - all_services = list(config.get('services', {}).keys()) 3. engine/cli/replay.py:327 - steps = list(replay_data.checkpoints.keys()) 4. engine/tools/secrets.py:452 - 'keys': list(secret_data.keys()) Dict views are directly iterable. list() creates unnecessary copy. FIX: Remove list() wrapper or use tuple() if indexing/slicing needed.