Fix NameError in ZeitwerkClassGetter for collapsed Zeitwerk paths

[KaiyuanMa]

Summary

Got an error when running annotaterb:

undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter
undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter
undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter
undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter
undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter
undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter
undefined local variable or method 'file' for an instance of AnnotateRb::ModelAnnotator::ZeitwerkClassGetter

The block on line 52 referenced a local variable file that does not exist in this scope. Any model file falling inside a Zeitwerk collapse path raised NameError: undefined local variable or method 'file', which was swallowed by the rescue NameError on line 77 and returned nil, silently breaking annotation for collapsed-path models.

Change

lib/annotate_rb/model_annotator/zeitwerk_class_getter.rb:52 — file.include?(...) → @file.include?(...).