Add cac-litespeed image family (OpenLiteSpeed, native LSAPI)

New paid-tier per-customer image built on litespeedtech/openlitespeed:1.8.4-lsphpNN.
Matrix: 8.1-8.5. Native LSAPI suexec to customer uid, server-level LSCache,
all WP/WooCommerce extensions (memcached, redis, imagick, mbstring, etc.) baked in.

Files:
- Dockerfile.litespeed (FROM prebuilt LiteSpeed base, layers wp-cli/composer/mariadb)
- configs/litespeed/{httpd_config,site-template,lsphp-overrides}.tpl
- scripts/{entrypoint,create-vhost,detect-memory}-litespeed.sh + install-lscache-wp.sh

CI: new Build-LiteSpeed-Images matrix job. OLS_VERSION pinned to 1.8.4 (only
release with prebuilt images for all 5 PHP versions on Docker Hub).

Spec: whp/docs/superpowers/specs/2026-06-01-cac-litespeed-design.md

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

scripts/detect-memory-litespeed.sh

@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+## detect-memory-litespeed.sh — sibling to detect-memory.sh.
+## Computes LSAPI_CHILDREN + extprocessor memSoftLimit/memHardLimit from
+## container memory cap. Sourced by entrypoint-litespeed.sh.
+
+## ---- container memory detection (mirrors detect-memory.sh) ----
+CONTAINER_MEMORY_BYTES=""
+
+if [ -f /sys/fs/cgroup/memory.max ]; then
+  val=$(cat /sys/fs/cgroup/memory.max 2>/dev/null)
+  if [ "$val" != "max" ] && [ -n "$val" ]; then
+    CONTAINER_MEMORY_BYTES=$val
+  fi
+fi
+
+if [ -z "$CONTAINER_MEMORY_BYTES" ] && [ -f /sys/fs/cgroup/memory/memory.limit_in_bytes ]; then
+  val=$(cat /sys/fs/cgroup/memory/memory.limit_in_bytes 2>/dev/null)
+  if [ -n "$val" ] && [ "$val" -lt 8589934592000 ] 2>/dev/null; then
+    CONTAINER_MEMORY_BYTES=$val
+  fi
+fi
+
+if [ -z "$CONTAINER_MEMORY_BYTES" ] && [ -f /proc/meminfo ]; then
+  mem_kb=$(awk '/^MemTotal:/ {print $2}' /proc/meminfo)
+  if [ -n "$mem_kb" ]; then
+    CONTAINER_MEMORY_BYTES=$((mem_kb * 1024))
+  fi
+fi
+
+if [ -z "$CONTAINER_MEMORY_BYTES" ]; then
+  CONTAINER_MEMORY_BYTES=$((512 * 1024 * 1024))
+fi
+
+CONTAINER_MEMORY_MB=$((CONTAINER_MEMORY_BYTES / 1024 / 1024))
+
+## ---- budget split (LSAPI workers get the lion's share) ----
+OS_RESERVE_MB=50
+OLS_RESERVE_MB=40    # OpenLiteSpeed daemon footprint
+DEV_OVERHEAD_MB=0
+if [ "${environment:-PROD}" = "DEV" ]; then
+  DEV_OVERHEAD_MB=125
+fi
+
+AVAILABLE_MB=$((CONTAINER_MEMORY_MB - OS_RESERVE_MB - OLS_RESERVE_MB - DEV_OVERHEAD_MB))
+if [ "$AVAILABLE_MB" -lt 60 ]; then
+  AVAILABLE_MB=60
+fi
+
+## ---- LSAPI children (analogous to PHP_FPM_MAX_CHILDREN) ----
+## LSAPI is more memory-efficient than FPM; estimate 96 MB / worker
+## (vs 128 MB for FPM after the 2026-06-01 bump). Floor 2, cap 50.
+LSPHP_WORKER_ESTIMATE_MB=${LSPHP_WORKER_ESTIMATE_MB:-96}
+
+calc_lsapi_children=$((AVAILABLE_MB / LSPHP_WORKER_ESTIMATE_MB))
+if [ "$calc_lsapi_children" -lt 2 ]; then
+  calc_lsapi_children=2
+fi
+if [ "$calc_lsapi_children" -gt 50 ]; then
+  calc_lsapi_children=50
+fi
+
+## Per-site override knobs — site-pool-env.php still passes FPM_MAX_CHILDREN
+## for backward compat, so prefer LSAPI_CHILDREN if set, else FPM_MAX_CHILDREN,
+## else the calculated value.
+LSAPI_CHILDREN=${LSAPI_CHILDREN:-${FPM_MAX_CHILDREN:-$calc_lsapi_children}}
+
+## extprocessor mem limits — total LSAPI heap should fit AVAILABLE_MB with
+## some breathing room. Soft = budget/children, hard = soft * 1.5, both capped
+## at 2047 (OLS interprets > 2047 oddly in some 1.x builds).
+LSAPI_MEM_SOFT=$((AVAILABLE_MB / LSAPI_CHILDREN))
+if [ "$LSAPI_MEM_SOFT" -lt 64 ]; then LSAPI_MEM_SOFT=64; fi
+if [ "$LSAPI_MEM_SOFT" -gt 2047 ]; then LSAPI_MEM_SOFT=2047; fi
+LSAPI_MEM_HARD=$((LSAPI_MEM_SOFT * 3 / 2))
+if [ "$LSAPI_MEM_HARD" -gt 2047 ]; then LSAPI_MEM_HARD=2047; fi
+
+export CONTAINER_MEMORY_MB LSAPI_CHILDREN LSAPI_MEM_SOFT LSAPI_MEM_HARD