Reduce idle PHP-FPM memory footprint

Opcache:
- memory_consumption: 128MB → 64MB (most WordPress sites use <40MB)
- max_accelerated_files: 10000 → 4000 (sufficient for WordPress)
- revalidate_freq: 2s → 60s (reduce stat() calls in production)
- enable_cli: Off (don't cache scripts run from command line)

FPM workers:
- process_idle_timeout: 10s → 5s (faster worker teardown when idle)
- max_requests: 500 → 200 (recycle workers sooner to release leaked memory)

These changes primarily reduce the baseline memory of idle containers
where opcache was reserving 128MB even for small sites.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

configs/prod-php.ini

@@ -1496,7 +1496,15 @@ ldap.max_links = -1
 ;dba.default_handler=
 
 [opcache]
-; see /etc/php.d/10-opcache.ini
+; Optimized for shared hosting — reduce idle memory footprint
+; Default 128MB is excessive for most WordPress sites
+opcache.memory_consumption = 64
+opcache.interned_strings_buffer = 8
+opcache.max_accelerated_files = 4000
+; Revalidate files every 60s in production (reduces stat() calls)
+opcache.revalidate_freq = 60
+; Don't waste memory on CLI scripts
+opcache.enable_cli = Off
 
 [curl]
 ; A default value for the CURLOPT_CAINFO option. This is required to be an