Fix job creation race condition

[ayushgupta704]

Description

This PR fixes the django-treebeard race condition reported in #3639, where concurrent Celery workers creating root jobs at the same time could lead to “ghost” roots and silent data loss.
While testing, I also noticed that nested job creation (parent.add_child()) was completely unprotected. In cases like parallel pivots or file drops, this could result in IntegrityError crashes.

• Added a database-level UniqueConstraint on Job.path so Postgres prevents duplicate entries.
• Wrapped both add_root and add_child in a retry loop (up to 10 attempts) with exponential backoff to handle collisions
  gracefully.
• On retries for child creation, the parent is refreshed from the database to ensure the latest numchild value is used.
• Added a fix_split_brain_jobs command to safely clean up any existing ghost jobs before applying the strict constraint.

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue).

Checklist

• I have read and understood the rules about how to Contribute to this project
• The pull request is for the branch develop
• I have inserted the copyright banner at the start of the file: ```# This file is a part of IntelOwl https://github.com/intelowlproject/IntelOwl # See the file 'LICENSE' for copying permission.

[ayushgupta704]

Hi @mlodic,
I Fix job creation race condition.
I’ve tested this under concurrent conditions and it’s working as expected now no more ghost roots parallel job creation.

Attaching test proof:
docker exec intelowl_uwsgi python manage.py test tests.api_app.test_views --keepdb (also tested parallel root and child job creation locally)

Screen.Recording.2026-04-10.130747.mp4

Screen.Recording.2026-04-10.135138.mp4

Everything seems to be running smoothly. Let me know if there’s anything else you’d like me to check.
This is ready for review
Thanks.