OrphanedBindingDetector discounted every reference that fell inside ANY registration, so the
registry pattern read as dead wiring: bind(Provider, fn ($app) => $app->make(Registry)->get(…))
is the only place naming the registry, and deleting it would break every Provider resolution.
Only a reference inside the registration OF THE SAME ABSTRACT proves nothing about demand — a
factory building the very thing it binds. ContainerBindings now keys registration spans by
abstract, so a different binding reaching for one counts like any type-hint.

Closes #389