Fix backup function to pass domain parameter

Bug fix in lib/php-config-manager.sh:
- Line 124: find_fpm_pool_config() requires both username AND domain
- Was only passing username, causing backup to fail
- Fixed: find_fpm_pool_config "$username" "$domain"

Impact:
- Backup functionality now works correctly
- Successfully backs up PHP-FPM pool configs
- Tested with pickledperil.com - backup created successfully

Verification:
- Syntax validated
- Backup test: passed
- Pool config found and backed up to /root/server-toolkit/backups/php/

lib/php-config-manager.sh

@@ -121,7 +121,7 @@ EOF
 
     # Backup FPM pool config
     local pool_config
-    pool_config=$(find_fpm_pool_config "$username")
+    pool_config=$(find_fpm_pool_config "$username" "$domain")
 
     if [ -n "$pool_config" ] && [ -f "$pool_config" ]; then
         local backup_path