Fix xdebug truthiness bug: preserve falsy value when disabled

When xdebug is disabled (xdebug: false), options.xdebug should remain
falsy (false) for backward compatibility. Previously, it was being set
to the string 'off' which is truthy in JavaScript, breaking any
downstream code that checks if (options.xdebug) to determine if
xdebug is enabled.

The fix ensures options.xdebug stays false when mode is 'off',
while still setting it to the mode string value when enabled.

Author: cursoragent

builders/php.js

@@ -284,7 +284,7 @@ const phpBuilder = {
       }
 
       options._xdebugConfig = normalizeXdebugConfig(options.xdebug);
-      options.xdebug = options._xdebugConfig.mode;
+      options.xdebug = options._xdebugConfig.mode !== 'off' ? options._xdebugConfig.mode : false;
       if (options._xdebugConfig.mode !== 'off') {
         const xdebugFile = path.join(options.confDest, options.defaultFiles.xdebug);
         fs.mkdirSync(options.confDest, {recursive: true});