feat(litespeed): wire up dynamic LSAPI tuning + idle reduction

Two correctness fixes and a tuning improvement.

CORRECTNESS:
1. Strip the stock 'extProcessor lsphp' from httpd_config.conf before
   appending ours. Previously the stock block (hard-coded
   PHP_LSAPI_CHILDREN=10 regardless of container memory) always won
   because our APPEND fragment didn't include an extProcessor block.
   detect-memory-litespeed.sh was computing LSAPI_CHILDREN but never
   plumbing it anywhere — silent dead code.

2. Bump LSPHP_WORKER_ESTIMATE_MB from 96 → 115 per the 2026-06-02
   memory-sizing finding (vantagehealth OOM-spawn loop). Each lsphp
   carries ~115 MB shmem-rss accounted per worker. 115 MB matches the
   real per-worker baseline.

TUNING (idle reduction, the original ask):
- LSAPI_MAX_IDLE_CHILDREN=2  (was CHILDREN/2 = 5 default)
- LSAPI_MAX_IDLE=60s         (was 300s default)
- PHP_LSAPI_MAX_REQUESTS=500 (recycle workers, prevents bloat)
- memSoftLimit=1024M / memHardLimit=1500M per worker (RLIMIT_AS;
  catches runaway scripts at the worker level, cgroup still backstops
  the container)

Effective LSAPI_CHILDREN per container:
  2 GiB → ~17 (was 10 — brain-jar was saturating)
  1 GiB → ~8
  512 MiB → ~3 (cap-marginal per the memory note; bump container if
                site grows)

Dropped LSAPI_MEM_SOFT/HARD computation in detect-memory: AVAILABLE/CHILDREN
was conflating VSZ with RSS-budget arithmetic and would have killed
legitimate workers. The 1024/1500 hard-coded values in the template
comfortably fit typical Divi/WooCommerce VSZ (280-365 MB).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

configs/litespeed/httpd_config.tpl

@@ -7,7 +7,8 @@
 ## append pattern too (see setup_docker.sh in litespeedtech/ols-dockerfiles).
 ##
 ## Rendered at container start by scripts/create-vhost-litespeed.sh via
-## envsubst. Templated vars: $user $domain $vhost_map_aliases.
+## envsubst. Templated vars: $user $domain $vhost_map_aliases $PHPVER
+##                           $LSAPI_CHILDREN (computed by detect-memory-litespeed.sh)
 
 ## --- our listeners (replace stock Default :8088) ---
 listener HTTP {
@@ -30,6 +31,53 @@ listener HTTPS {
   map                     siteVH *
 }
 
+## --- lsphp extProcessor (overrides the stock one which is hard-coded to
+## PHP_LSAPI_CHILDREN=10 regardless of container memory).
+##
+## Sized dynamically by detect-memory-litespeed.sh based on the cgroup cap:
+##   2 GiB container → LSAPI_CHILDREN ≈ 17  (was stuck at 10)
+##   1 GiB container → LSAPI_CHILDREN ≈ 8
+##   512 MiB         → LSAPI_CHILDREN ≈ 3
+##
+## Idle-reduction knobs (the question that motivated this whole block):
+##   LSAPI_MAX_IDLE_CHILDREN=2   default was CHILDREN/2 (so 10/2=5)
+##   LSAPI_MAX_IDLE=60           default was 300 (5 min)
+## Together: max 2 idle workers kept alive, anything idle >60s gets reaped.
+## Trade-off: cold-start of an extra worker after idle reaping costs ~50-100ms
+## on the first request to it. Worth it for shadowdao-sized low-traffic sites
+## where the difference is "30 MB idle" vs "200 MB idle".
+##
+## memSoftLimit/memHardLimit: per-worker RLIMIT_AS catches a runaway PHP
+## script before it hogs the whole pool's memory. Cgroup is still the host
+## backstop (one-customer-per-container), but the per-worker cap protects
+## the OTHER workers in the same pool from a bad-actor script. 1024M soft
+## comfortably accommodates typical Divi/WooCommerce VSZ (~280-365 MB).
+extProcessor lsphp {
+  type                    lsapi
+  address                 uds://tmp/lshttpd/lsphp.sock
+  maxConns                ${LSAPI_CHILDREN}
+  env                     PHP_LSAPI_CHILDREN=${LSAPI_CHILDREN}
+  env                     LSAPI_MAX_IDLE_CHILDREN=2
+  env                     LSAPI_MAX_IDLE=60
+  env                     PHP_LSAPI_MAX_REQUESTS=500
+  env                     LSAPI_AVOID_FORK=200M
+  initTimeout             60
+  retryTimeout            0
+  persistConn             1
+  pcKeepAliveTimeout      30
+  respBuffer              0
+  autoStart               1
+  path                    /usr/local/lsws/lsphp${PHPVER}/bin/lsphp
+  backlog                 100
+  instances               1
+  runOnStartUp            1
+  priority                0
+  memSoftLimit            1024M
+  memHardLimit            1500M
+  procSoftLimit           400
+  procHardLimit           500
+}
+
 ## --- our vhost via vhTemplate (upstream's working pattern) ---
 ## The template file is /usr/local/lsws/conf/templates/site.conf — written
 ## by create-vhost-litespeed.sh at the same time as this fragment.