v1.0.1

Fixed

• Singleton returns to the ecosystem-standard storage shape:
  protected static $instance, stored by get_instance() once the constructor
  returns. The class-string-keyed private map introduced for 1.0.0 broke a real
  consumer contract — a heavy constructor assigning static::$instance = $this;
  first so work done during construction can re-enter get_instance(), which
  fataled theme-elementary on 1.0.0 with "Access to undeclared static property".
  That early-assignment guard is now the documented, tested pattern. Trade-off,
  also documented on the trait: a class using the trait and its subclasses share
  one storage slot, so do not call get_instance() on a subclass of a singleton.

Full changelog: v1.0.0...v1.0.1