No E2E tests for artifact push/pull/copy commands

[brandonrc]

Problem

7 command modules lack E2E tests. The artifact commands (push, pull, list, search, copy) are the primary user workflow and have zero integration coverage. Regressions in these paths are only caught by users.

Suggested Fix

Add E2E tests that run against a real backend instance:

1. artifact push with various formats
2. artifact pull and verify checksum
3. artifact list and verify output format
4. artifact search with query terms
5. artifact copy between repositories

Use the existing CI docker-compose setup to provide the backend service.

Source

Quality audit, 2026-03-23.