Audit Chain 1.0.2

Declares the PHP floor in composer.json: >=8.1.

Checked rather than assumed. PHPCompatibility reports the codebase clean from
8.1 upward, Drupal 10.6 requires >=8.1.0, and neither drupal/key nor
drupal/encrypt declares a PHP constraint of its own. The drupalcode
previous-major lane already runs this suite on PHP 8.1.34 and passes.

No resolution outcome changes today; the declared core range already implies
the same floor.