- docs/architecture.md: replace fmt.Errorf with coreerr.E() to match actual implementation
- cache_test.go: add TestGitHubKeys for GitHubReposKey/GitHubRepoKey (was 0% coverage)
- cache_test.go: add TestPathTraversalRejected for Path() traversal guard
Co-Authored-By: Virgil <virgil@lethean.io>