PR #15: harden monitor-freshness thresholds and network retries

[khalidsaidi]

Summary

Hardens monitor-freshness.yml to reduce false alarms and enforce exact thresholds.

Changes

• add network resilience to stats fetch:
  • --retry 3
  • --retry-all-errors
  • --retry-delay 2
  • --connect-timeout 10
  • --max-time 30
• switch age checks from floored hours to exact seconds:
  • ingest fails when ageSec > 36 * 3600
  • reachability fails when ageSec > 18 * 3600
• keep hour output for readability, add second output for precision.

Why

• avoids edge-case drift where 36h59m could pass due to integer hour flooring
• reduces transient public-network failures causing noisy monitor alerts

Validation

• reviewed workflow YAML/script logic
• no runtime/API code changes