Commands are now hidden from help and return ErrUnknownCommand when
invoked if their hook is nil (and for version, if Version string is
also empty). No explicit DisabledCommands needed for MCPs that don't
use login/setup/config/etc.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Commands listed in DisabledCommands are excluded from global help output
and return ErrUnknownCommand when invoked or help is requested for them.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>