obleth-gateway v0.9.4

The v0.9.3 self-heal fix now actually reaches deployments, and failed job cancellations say why.

• Deployment defaults no longer undo the v0.9.3 self-heal fix. The docker-compose fallback, the Helm chart default, and the env example all still pinned OBLETH_PROVISIONER_RESTART_AFTER_FAILURES=3, silently overriding the binary's new default — so provisioners deployed from them kept cancelling healthy replicas after ~45 seconds of probe flaps. All three now default to 20 (~5 minutes of sustained failure at the default tick interval). If you set the variable to 3 yourself, remove or raise it when upgrading.
• Cancel failures report the real reason. When slurmrestd refuses to cancel a job, the provisioner now logs the response body (e.g. Access/permission denied from slurm_kill_job2) instead of only the HTTP status — a bare 500 previously hid actionable causes like a JWT user / job owner mismatch.