atrium 0.37.2

Fixed

• fleet up refused every roster whose cmd is a configured claude alias.
  0.37.1 began vetting each agent's cmd at launch with the ctl spawn policy,
  and that policy matched the literal stem claude while is_agent_stem already
  counted an alias from claude_aliases as an agent, so a second account's shim
  such as claude2 fell into the "no trust posture is defined for it" refusal
  written for aider and gemini. The vet now asks is_claude_stem, the same
  test binding and status use, so any stem the operator lists in claude_aliases
  (the config file, ATRIUM_CLAUDE_ALIASES, or the fleet) takes claude's flag
  policy and claude's posture. Governed flags are still stripped from an alias
  and unlisted ones still refused, exactly as for claude.