Motivation

• Remove backend-specific job construction from the base Queue and centralize dependency normalization and registration logic to eliminate duplication.
• Keep base_queue.Queue backend-agnostic so submit() no longer imports or references serial_queue.
• Make lightweight backends (Serial/TMUX) and heavyweight backends (Slurm/Airflow) provide a small job-factory hook so common behaviors are shared.
• Preserve the public API (Queue.create, submit, sync, print_commands, print_graph, etc.) and existing runtime behavior.

Description

• Added backend hooks and helpers to base_queue.Queue: _new_job, _default_job_name, _normalize_depends, _apply_all_depends, and _register_job, and refactored submit() to use them.
• Implemented _new_job(...) in serial_queue.SerialQueue, tmux_queue.TMUXMultiQueue, slurm_queue.SlurmQueue, and airflow_queue.AirflowQueue so each backend constructs its own job types and default naming.
• Removed duplicated dependency normalization/registration logic from Slurm and Airflow submit implementations and made them rely on the shared base submit() flow.
• Kept Queue.create() as the single import hub for backend classes and ensured behavior and name-uniqueness checks remain unchanged.

Testing

• No automated tests were executed as part of this refactor.
• Changes were implemented to be behavior-preserving and designed to pass the existing test suite without requiring API updates.
• Suggested follow-up: run the repository test suite via python run_tests.py or pytest tests to validate integration with environment-specific backends.
• Tmux/slurm/airflow dependent tests remain subject to their respective system availability checks.

Codex Task