after #4083 the staleness window is 30 minutes, which still lets an ip
that stopped connecting a few minutes ago sit in the db blob and keep
the protected slot on the ascending sort. the ip that is actually
connecting right now gets classified as excess and sent to fail2ban,
and never lands in inbound_client_ips.ips so the panel doesnt show it
until you clear the log by hand.
only count ips observed in the current scan toward the limit. db-only
entries stay in the blob for display but dont participate in the ban
decision. live subset still uses the "protect oldest, ban newcomer"
rule.
closes#4091. followup to #4077.
