debugOverrideDylibPath property
Test-only: override the dylib path that _ensureBindings uses on
the first call. Set this from unit tests that run in a plain Dart VM
(no Native Assets framework bundle); leave null in production.
Setting after the first FFI call has no effect — the bindings are
cached. Reset to null + null out _bindings if a test really needs
to swap the dylib mid-process.
Implementation
@visibleForTesting
static String? debugOverrideDylibPath;