Optimize Apache & PHP-FPM memory for lower idle usage

Switch PHP-FPM from pm=dynamic to pm=ondemand (zero idle workers),
auto-detect container memory via cgroups to calculate appropriate
limits, and generate Apache MPM config at runtime. All tuning values
are now overridable via environment variables.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/create-apache-mpm-config.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+# Generate Apache MPM event tuning config at runtime using detect-memory.sh values.
+
+cat <<EOF > /etc/httpd/conf.d/mpm-tuning.conf
+<IfModule mpm_event_module>
+    StartServers            ${APACHE_START_SERVERS}
+    MinSpareThreads         ${APACHE_MIN_SPARE_THREADS}
+    MaxSpareThreads         ${APACHE_MAX_SPARE_THREADS}
+    ThreadLimit             64
+    ThreadsPerChild         25
+    MaxRequestWorkers       ${APACHE_MAX_REQUEST_WORKERS}
+    ServerLimit             ${APACHE_SERVER_LIMIT}
+    MaxConnectionsPerChild  ${APACHE_MAX_CONNECTIONS_PER_CHILD}
+</IfModule>
+EOF
+
+exit 0