Detect circular self-resolution instead of StackOverflowError

[muhammadkamel]

Summary

• Detect when a registration's factory re-enters the same type (common footgun: registerLazySingleton<Iface>(getIt.call) / untyped tear-offs) and throw a clear StateError instead of overflowing the stack.
• Avoid eager $stackTrace interpolation in creation-error debug logging when GetIt.noDebugOutput is set (that path can make release crash dumps look "native").
• Add regression tests and a short README note with the safe pattern (() => getIt<Impl>()).

Motivation

In production, registering an untyped tear-off of call/get as a factory for interface T recursively calls get<T>() until StackOverflowError. Some crash reporters then drown in StackTrace.toString work, which obscured the real DI bug.

Test plan

• dart test test/circular_self_resolution_test.dart
• dart test (full suite)
• Confirm message points authors at () => getIt<Impl>() / named tear-offs

[muhammadkamel]

Follow-up: fixed a Bugbot finding where overlapping getAsync on the same async factory was falsely treated as circular dependency. The creation guard now only covers the synchronous factory start (lazy async still holds until the pending creation finishes). Added regression tests.