Adds per-monitor `retries` and `retryDelayMs` options. When a check fails,
the monitor is re-checked up to `retries` extra times (waiting `retryDelayMs`
between attempts, default 5000ms) before being reported as down. This filters
out transient blips / false positives, and affects both the status page state
and downtime notifications.
Backward compatible: default `retries: 0` keeps the current behavior (no retry).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Globalping rejects measurementOptions.ipVersion when the measurement target is an IP address.
Add an IP-target guard so ipVersion is only sent for domain targets, preventing validation errors when checking IP:port monitors.