Add restart option for failed/dismissed jobs

[freds-dev]

Related to #41

Paired with eo-tools/eozilla-app#72.

Adds POST /jobs/{jobId}/restart to create a new job from the original request of a failed or dismissed job.

• Adds the restart operation to the OpenAPI contract and generated service/routes.
• Supports restart in the local service by retaining the original process request.
• Supports restart in the Airflow service by replaying the original DAG-run configuration.
• Rejects restarts for accepted, running, and successful jobs.

Checklist (strike out non-applicable):

• Changes documented in CHANGES.md
• Related issue exists and is referred to in the PR description and CHANGES.md
• Added docstrings and API docs for any new/modified user-facing classes and functions
• Changes/features documented in docs/*
• Unit-tests adapted/added for changes/features
• Test coverage remains or increases (target 100%)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[freds-dev]

Service was moved from gavicore/service.py to gavicore/service/service.py, but the generator still used the old relative import.