fix(lsphp): set LSAPI_KEEP_LISTEN=2 to stop idle-exit timing from following the leaked busy counter

lsphp's master keeps a `busy` worker counter in a MAP_SHARED page that drifts
negative over days of uptime (measured live on whp01: busy=-8 after 6.9 days
on arclightcourt.com-01 vs 0..9 on a healthy sibling). php-src's
sapi/litespeed/lsapilib.c derives each child's idle-exit grace period from
that counter (10 + busy*10, capped by LSAPI_MAX_IDLE) only inside
`if (s_keep_listener == 1)`; with busy=-8 that's -70s, so workers exit after
~1s idle instead of 10-30s, no worker ever lingers in accept(), the
"don't fork, one's already listening" guard never fires, and the master
forks for every connection -- confirmed hitting the max-children ceiling and
producing 503s under bot traffic (306 OLS-side ExtConn-timeout/503 errors on
the affected site vs 0 on an identical healthy sibling).

LSAPI_KEEP_LISTEN=2 skips the `== 1` branch entirely so idle-exit timing
falls back to LSAPI_MAX_IDLE (already 30 by default here) instead of the
leaked counter. is_enough_free_mem() sits above that branch, not inside it,
so the memory-pressure guard is unaffected.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/entrypoint-lsphp.sh

@@ -109,6 +109,32 @@ export PHP_LSAPI_MAX_REQUESTS="${PHP_LSAPI_MAX_REQUESTS:-500}"
 export LSAPI_MAX_IDLE="${LSAPI_MAX_IDLE:-30}"
 export LSAPI_EXTRA_CHILDREN="${LSAPI_EXTRA_CHILDREN:-5}"
 export LSAPI_AVOID_FORK="${LSAPI_AVOID_FORK:-0}"
+## LSAPI_KEEP_LISTEN=2 works around a leak in lsphp's own bookkeeping — not a
+## setting we're tuning for taste. The master keeps a `busy` worker counter in
+## a MAP_SHARED page it shares with its children; measured live on whp01,
+## that counter drifts NEGATIVE over days of uptime (arclightcourt.com-01 was
+## at busy=-8 after 6.9 days; a healthy sibling sat at 0..9). php-src
+## sapi/litespeed/lsapilib.c computes each child's idle-exit grace period as
+## `10 + busy*10` seconds (capped by LSAPI_MAX_IDLE) INSIDE
+## `if (s_keep_listener == 1)` — with busy=-8 that's `wait_time = -70`, so
+## workers exit after ~1s idle instead of 10-30s. No worker then lingers in
+## accept(), so the master's "an idle worker is already accepting, don't
+## fork" guard never fires and it forks for every single connection —
+## observed slamming the hard child ceiling under bot traffic
+## (`Reached max children process limit`) and, on rejection, leaving the
+## pending connection to rot in the kernel backlog as a 503. Confirmed
+## asymmetry: the affected site logged 306 OLS-side `ExtConn timed out` /
+## deadlock / `oops! 503` errors where an identically-configured healthy
+## sibling logged 0. Restarting the container resets the counter to 0 (it's
+## initialised at master start) but it drifts negative again over about a
+## week — a reset, not a cure. LSAPI_KEEP_LISTEN=2 skips the `== 1` branch
+## entirely, so idle-exit timing is never derived from the leaked counter and
+## instead falls straight back to LSAPI_MAX_IDLE above. The is_enough_free_mem()
+## memory guard sits immediately above that branch in lsapilib.c and is NOT
+## part of it, so it still applies at =2 — this does not trade away the
+## memory-pressure protection LSAPI_MAX_IDLE exists for. Still overridable
+## (e.g. back to 1) per-container as an escape hatch.
+export LSAPI_KEEP_LISTEN="${LSAPI_KEEP_LISTEN:-2}"
 LSPHP_BIND="${LSPHP_BIND:-0.0.0.0:9000}"
 
 ## ---- .user.ini support ----
@@ -130,7 +156,7 @@ LSPHP_BIND="${LSPHP_BIND:-0.0.0.0:9000}"
 ## .user.ini has not been remediated yet.
 export LSPHP_ENABLE_USER_INI="${LSPHP_ENABLE_USER_INI:-on}"
 
-echo "Container memory: ${CONTAINER_MEMORY_MB}MB | PHP_LSAPI_CHILDREN=${PHP_LSAPI_CHILDREN} | LSAPI_MAX_IDLE=${LSAPI_MAX_IDLE} | PHPVER=${PHPVER} | bind=${LSPHP_BIND} | user_ini=${LSPHP_ENABLE_USER_INI}"
+echo "Container memory: ${CONTAINER_MEMORY_MB}MB | PHP_LSAPI_CHILDREN=${PHP_LSAPI_CHILDREN} | LSAPI_MAX_IDLE=${LSAPI_MAX_IDLE} | LSAPI_KEEP_LISTEN=${LSAPI_KEEP_LISTEN} | PHPVER=${PHPVER} | bind=${LSPHP_BIND} | user_ini=${LSPHP_ENABLE_USER_INI}"
 
 ## Validate a numeric value destined for a generated php.ini fragment.
 ## Sets INI_NUM to the value when it is acceptable, and to "" (plus a WARNING)