Bash arithmetic comparison `[ "$CHAINS" -gt 0 ]` on potentially empty string in fleet postflight

Opus finding

Bash arithmetic comparison `[ "$CHAINS" -gt 0 ]` on potentially empty string in fleet postflight

• .github/workflows/aeon.yml:360-369

If the response is HTTP 201 but the body lacks a `chainsDetected` field, jq emits `null | length` which yields 0 — okay. But if the body is malformed (jq fails), CHAINS could be empty, and `[ "" -gt 0 ]` triggers a bash error under `set -euo pipefail`, failing the always-runs postflight step and turning a non-fatal signal into a job failure. The step is gated `if: always()` and is supposed to be non-fatal; an exit here will mark the job failed even though the skill ran successfully.