Add Resolver type with comprehensive address resolution:
- Direct agent addresses (contains '/')
- Pattern matching (*/witness, gastown/*)
- @-prefixed patterns (@town, @crew, @rig/X)
- Beads-native groups (gt:group beads)
- Name lookup: group → queue → channel
- Conflict detection with explicit prefix requirement
Implements resolution order per gt-xfqh1e epic design:
1. Contains '/' → agent address or pattern
2. Starts with '@' → special pattern
3. Otherwise → lookup by name with conflict detection
Part of gt-xfqh1e.5 (address resolution task).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
