Add AppendRouteToDir helper and use it to add hq-* route during rig
initialization. This allows rig beads to resolve role beads and other
hq-* prefixed beads stored in town beads.
Uses safe append pattern (load, merge, write) instead of overwriting
to avoid clobbering future rig routes.
Supersedes PR #184 with proper implementation.
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
03fef16748