feat: queued jobs table in database

[marius-mather]

Pull Request

Summary

SBP-422: add a queued_jobs table to the database, so the web service can write jobs to the queue, to be picked up by the scheduler.

Changes

• QueuedJob database model
• Workflow launch endpoint writes queued jobs to the database (interim step before we offload these to the job queue)
• Refactor some existing workflow launch code to reduce duplication

How to Test

Run uv run pytest

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have added tests that prove my fix is effective or that my feature works
• I have added or updated documentation where necessary
• I have run linting and unit tests locally
• The code follows the project's style guidelines

[amandazhuyilan]

Looks good but reminder to please update the database diagram with generate_db_diagram.sh.

[vtnphan]

Look s good to me! Thanks for refactoring the workflow executors ^_^