feat: implement Christmas Ornament pattern for mol-witness-patrol (gt-tnow.1, gt-tnow.2)

- Update WitnessPatrolMolecule() with dynamic bonding pattern:
  - PREFLIGHT: inbox-check, check-refinery, load-state
  - DISCOVERY: survey-workers (bonds mol-polecat-arm per polecat)
  - CLEANUP: aggregate (WaitsFor: all-children), save-state, generate-summary,
    context-check, burn-or-loop
  - Reduced from 11 sequential steps to 9 with parallel arm execution

- Add PolecatArmMolecule() for per-polecat inspection:
  - 5 sequential steps: capture, assess, load-history, decide, execute
  - Uses {{polecat_name}} and {{rig}} variable substitution
  - Bonded dynamically by survey-workers step

- Update tests: 14 builtin molecules, new test cases

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

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

internal/beads/builtin_molecules.go

@@ -26,6 +26,7 @@ func BuiltinMolecules() []BuiltinMolecule {
 		DeaconPatrolMolecule(),
 		RefineryPatrolMolecule(),
 		WitnessPatrolMolecule(),
+		PolecatArmMolecule(),
 
 		// Session and utility molecules
 		CrewSessionMolecule(),