Migrated 39 test files covering CLI integration and unit testing:
- 6 new integration tests (auth-resolution, concurrency, cross-command, inventory-resilience, multi-registry, version-upgrade-flow)
- Enhanced 7 existing integration tests with comprehensive scenarios
- Updated 2 unit tests with correct exit code expectations
All tests use fake registry approach (no E2E/browser required) and pass lint/build/test checks.
