php-fpm: refactor with deterministic config files & improved debug

php-fpm/7.4/www.conf

@@ -41,6 +41,10 @@ request_terminate_timeout = 300s
 request_slowlog_timeout = 5s
 slowlog = /var/log/php/www-slow.log
 
+; Force all PHP errors into the container log stream so kubernetes/docker can collect them.
+php_admin_flag[log_errors] = on
+php_admin_value[error_log] = /proc/self/fd/2
+
 ; Redirect worker stdout and stderr to the main error log.
 ; This ensures that any `echo` or `var_dump` calls from workers are captured in the container logs.
 catch_workers_output = yes