hq-u0ach: done.go - Add --cleanup-status flag so agents can pass cleanup
status directly. Removes computeCleanupStatus() which violated ZFC by
having Go compute cleanup status from git state.
hq-z0zqw: beads.go - Remove strings.Contains parsing for ErrNotARepo and
ErrSyncConflict. Per ZFC, Go should transport errors to agents, not parse
them to make decisions. IsBeadsRepo() now uses file existence check.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>