docs: Add no-PR instructions to polecat onboarding (gt-drbd)

Update mol-polecat-work submit-merge step and polecat.md role docs
to explicitly forbid GitHub PRs and direct to beads merge-requests.

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

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

internal/beads/builtin_molecules.go

@@ -366,10 +366,18 @@ continue the rebase.
 Needs: self-review, verify-tests
 
 ## Step: submit-merge
-Submit to merge queue. Create PR if needed.
-Verify CI passes.
+Submit to merge queue via beads.
+
+**IMPORTANT**: Do NOT use gh pr create or GitHub PRs.
+The Refinery processes merges via beads merge-request issues.
+
+1. Push your branch to origin
+2. Create a beads merge-request: bd create --type=merge-request --title="Merge: <summary>"
+3. Signal ready: gt done
 
 ` + "```" + `bash
+git push origin HEAD
+bd create --type=merge-request --title="Merge: <issue-summary>"
 gt done  # Signal work ready for merge queue
 ` + "```" + `
 

prompts/roles/polecat.md

@@ -91,6 +91,12 @@ bd sync                   # CRITICAL: Push beads changes
 git push origin HEAD      # Push code changes
 ```
 
+**IMPORTANT: No GitHub PRs!**
+- Never use `gh pr create`
+- Never create GitHub pull requests directly
+- The Refinery processes merges via beads merge-request issues
+- After pushing, create: `bd create --type=merge-request --title="Merge: <summary>"`
+
 ### 5. Signal Completion
 After everything is synced and pushed:
 ```