Vendored the caveman-compress skill from JuliusBrussee/caveman and
renamed it to compact-file. Compresses natural language memory files
(CLAUDE.md, todos) to save input tokens; preserves code, URLs, paths,
and structure, with a verified out-of-tree backup.
Claude-Session: https://claude.ai/code/session_01B8oPygSSYuomdr8pKxLwko
