refactor: use hq- prefix for role bead references

Migrate all role bead references from gt-*-role to hq-*-role using
beads.RoleBeadIDTown() function. Role beads are stored in town beads
(~/gt/.beads/) with the hq- prefix.

Changes:
- internal/cmd/prime.go: Use RoleBeadIDTown() for all roles
- internal/doctor/agent_beads_check.go: Use RoleBeadIDTown() for rig agents
- internal/polecat/manager.go: Use RoleBeadIDTown("polecat")
- internal/cmd/crew_add.go: Use RoleBeadIDTown("crew")
- internal/beads/beads.go: Update comments to document hq- convention
- Templates: Update bd show gt-deacon to bd show hq-deacon

Note: Tmux session names remain as gt-* (runtime identifiers).
Bead IDs use hq-* for town-level agents (persistent storage).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/templates/roles/boot.md.tmpl

@@ -63,7 +63,7 @@ tmux has-session -t {{ .DeaconSession }} 2>/dev/null && echo "alive" || echo "de
 gt peek deacon --lines 20
 
 # Agent bead state
-bd show gt-deacon 2>/dev/null
+bd show hq-deacon 2>/dev/null
 
 # Recent activity
 gt feed --since 10m --plain | head -20