libcurl overrides an existing host:port DNS cache entry each time a new
one is added, so one entry per address left only the last pinned. That is
IPv6 whenever the target has AAAA records, which broke every request on
hosts without IPv6. Join them into one comma separated entry instead.
S3 backup uploads fail when the endpoint has an AAAA record: mc parses
--resolve values with netip.ParseAddr and rejects the bracketed IPv6
form. Its resolver map also keeps only one IP per host, so emit a single
entry, preferring IPv4, without brackets.
Add SafeWebhookUrl validation rule to notification webhook URL fields
(Slack, Discord, custom webhook) to enforce safe URL patterns including
scheme validation and hostname checks.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
