The per-source host table only grew: once its fixed open-addressed table
filled, host_intern returned -1 and the per-host cap plus the shared auth
lockout silently failed open forever. Add a bounded-lifetime eviction
policy: track a per-bucket last-use time and, when no empty bucket exists,
atomically repurpose the first bucket that has no active connection and
either has an expired lockout or has been idle, resetting its counters.
Warn (rate-limited) on the genuine fail-open path.
A child SIGKILLed mid-registration could also leak a module/host count
because the parent only decremented on a REGISTERED slot. Make the slot
table the source of truth: after the SIGCHLD reap the parent recomputes
module_active[]/host_active[] from the surviving REGISTERED slots (atomics
only, async-signal-safe) so any leaked increment is erased.
Also clamp module_count to DAEMON_LIMITS_MAX_MODULES and use one helper
for the sizing/register host-tracking condition (a lockout threshold with
duration 0 is a no-op and must not intern hosts).