* Add Healthchecks.io notify hook
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
* notify/healthchecks: require an exact "OK" response
hc-ping.com answers HTTP 200 "OK (not found)" for an unknown UUID, so the
prefix match reported success for a mistyped or deleted check, including
the --set-notify test ping. Only treat an exact "OK" body as success.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 5 <noreply@anthropic.com>