e1bc648dfc
Add comprehensive unit tests for the certificate upload, export, and detail management feature: - CertificateExportDialog: 21 tests covering format selection, blob download, error handling, and password-protected exports - CertificateUploadDialog: 23 tests covering file validation, format detection, drag-and-drop, and upload flow - CertificateDetailDialog: 19 tests covering detail display, loading state, missing fields, and branch coverage - CertificateChainViewer: 8 tests covering chain visualization - CertificateValidationPreview: 16 tests covering validation display - FileDropZone: 18 tests covering drag-and-drop interactions - useCertificates hooks: 10 tests covering all React Query hooks - certificates API: 7 new tests for previously uncovered endpoints Fix null-safety issue in ProxyHosts where cert.domains could be undefined, causing a runtime error on split(). Frontend patch coverage: 90.6%, overall lines: 89.09%