destroySingletons method
Destroys all singleton pods in the factory.
This method calls destruction callbacks on all singleton pods and clears the singleton registry. Useful for application shutdown.
Usage Example:
// During application shutdown
await factory.destroySingletons();
Implementation
@override
void destroySingletons() {
// lifecycle ops stay local; do not force parent to run its lifecycle from a child
getPodFactory().destroySingletons();
}