Revert .gitignore changes and move opcache optimization to separate code section

Co-authored-by: samdark <[email protected]>

Author: Copilot

.gitignore

@@ -16,7 +16,4 @@ Thumbs.db
 .DS_Store
 
 # po4a .mo files
-*.mo
-
-# Vale temporary styles
-.github/styles/Microsoft/
+*.mo

guide/en/tutorial/performance-tuning.md

@@ -15,6 +15,11 @@ A well-configured PHP environment is important. To get maximum performance:
 - [Tune `realpath()` cache](https://github.com/samdark/realpath_cache_tuner).
 - Make sure [XDebug](https://xdebug.org/) isn't installed in the production environment.
 - Try [PHP 7 preloading](https://wiki.php.net/rfc/preload).
+
+## Optimizing your code <span id="optimizing-code"></span>
+
+Beyond environment configuration, there are code-level optimizations that can improve your application's performance:
+
 - Use fully qualified function names with leading backslashes to optimize opcache performance.
   When calling global functions from within a namespace, PHP first searches in the current namespace
   before falling back to the global namespace. Adding a leading backslash (e.g., `\count()` instead of `count()`)