fix(artifact): drop joinLines, which joinLinesExcept replaced The flag-aware version took over every call site, so the wrapper was dead the moment it was written. Caught by golangci-lint's `unused`, which does not run on the machine this was written on. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DmGyL6QvamMBKdHYyrx7Uq