This file ensures tests/fixtures/audit_inputs/ is tracked in git. The 6 input JSON files (audit_weak_types.json, audit_exception_handling.json, audit_optional_in_3_files.json, audit_no_models_config_io.json, audit_main_thread_imports.json, type_registry.json) are populated in Phase 10. The .gitkeep is removed when the first JSON file is added.