Promote org/project/repo/grant out of labs

Make the control-plane command groups visible in root help instead of only discoverable via entire labs:

• Drop Hidden: true from the org, project, repo, and grant groups and update their doc comments (no more "surfaced via labs").
• Remove the four entries (and their --help lines) from the labs experimental-command registry.
• Update root.go registration comments and the CLAUDE.md command layout.