fix: SystemController php-fpm detection — probe phpX.Y-fpm from running PHP version first

TODO.md

@@ -2,3 +2,4 @@
 
 ## Fixes
 - [x] Replace `mb_strlen`/`mb_substr` with `strlen`/`substr` in TfeController, SearchController, Parsedown — mbstring extension not available on production server
+- [x] SystemController: PHP-FPM status check — dynamically probe `phpX.Y-fpm` unit derived from running PHP version before static fallback list; add `php8.4-fpm` to cover current production PHP 8.4