Add PATCH /jobs/{job_id} support and align batch job deletion semantics

[Copilot]

The driver exposed PATCH /jobs/{job_id} but returned FeatureUnsupported, and job deletion in the dummy backend did not actually remove stored job state. This PR wires backend-level job patching into the API and makes delete behavior consistent with endpoint intent.

• API surface: enable job modification endpoint

  • PATCH /jobs/{job_id} now delegates to batch_jobs.update_job(...) and returns 204.
  • Endpoint visibility in capabilities is now conditional (hidden=is_not_implemented(...)) instead of always hidden.
  • Added BatchJobs.update_job(job_id, user_id, data) to the backend contract (default @not_implemented).

• Dummy backend: implement update/delete behavior

  • Added DummyBatchJobs.update_job(...) with spec-aligned constraints:
    • rejects updates for queued/running jobs via JobLocked.
    • accepts only editable fields: title, description, process, plan, budget.
    • rejects non-editable fields via PropertyNotEditable.
  • Updated DummyBatchJobs.delete_job(...) to remove both job metadata and result metadata entries.

• Tests: cover new endpoint and behavior

  • Capabilities now expect PATCH on /jobs/{job_id}.
  • Added focused tests for:
    • successful patch updates,
    • locked-job rejection,
    • read-only-property rejection,
    • delete removing registry state.

@api_endpoint(hidden=is_not_implemented(backend_implementation.batch_jobs.update_job))
@blueprint.route('/jobs/<job_id>', methods=['PATCH'])
@auth_handler.requires_bearer_auth
def modify_job(job_id, user: User):
    backend_implementation.batch_jobs.update_job(job_id=job_id, user_id=user.user_id, data=request.get_json())
    return response_204_no_content()