Add type=group to beads schema for mail distribution groups.
Fields:
- name: unique group identifier
- members: addresses, patterns, or group names (can nest)
- created_by: provenance tracking
- created_at: timestamp
Groups support:
- Direct addresses (gastown/crew/max)
- Patterns (*/witness, @crew)
- Nested groups (members can reference other groups)
Part of gt-xfqh1e epic (beads-native messaging).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>