shared-workspace-agent-harness

Keep code in git, not in the synced document folder. Sweep a folder for git repos + worktrees, verify branches are on a remote, prune pushed worktrees, and flag code/deps/secrets that leaked into a cloud-sync document library. Powered by the `hygiene` binary. Triggers on "repo hygiene", "clean up worktrees", "is everything pushed", "code leaked into Dropbox/Drive", "prune worktrees", "add the harness to this project".