fix: remove bd sync from polecat startup sequence (gt-aobh)

Polecats share the same beads database at the rig level. The refinery
and witness manage syncing beads. Running bd sync on polecat startup
causes contention when multiple polecats spawn simultaneously and
creates potential race conditions.

This change removes bd sync --from-main from:
- prompts/roles/polecat.md On Startup section
- internal/beads/molecules_session.go orient step
- internal/beads/molecules_work.go orient step
- docs/polecat-wisp-architecture.md load context section

Troubleshooting sections that recommend bd sync --from-main for
recovery scenarios are preserved.

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

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

docs/polecat-wisp-architecture.md

@@ -146,7 +146,6 @@ Read polecat.md protocol. Understand:
 
 Load context:
 - gt prime
-- bd sync --from-main
 - gt mail inbox
 
 ## Step: handoff-read