Formula scaffold beads (created when formulas are installed) were
appearing as actionable work items in `gt ready`. These are template
beads, not actual work.
Add filtering to exclude issues whose ID:
- Matches a formula name exactly (e.g., "mol-deacon-patrol")
- Starts with "<formula-name>." (step scaffolds like "mol-deacon-patrol.inbox-check")
The fix reads the formulas directory to get installed formula names
and filters issues accordingly for both town and rig beads.
Fixes: gt-579
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
