fix: Refinery queue uses beads MQ as source of truth (hq-eggh5)

The refinery was checking git branches instead of the beads merge queue.
This caused MRs to pile up when branches were deleted but MR beads remained.

- manager.go: Queue() now queries beads for type=merge-request issues
- refinery.md.tmpl: Updated queue-scan to use gt mq list
- mol-refinery-patrol.formula.toml: Updated queue-scan step instructions

.beads/formulas/mol-refinery-patrol.formula.toml

@@ -99,27 +99,28 @@ id = "queue-scan"
 title = "Scan merge queue"
 needs = ["inbox-check"]
 description = """
-Review the queue built from MERGE_READY messages in inbox-check.
+Check the beads merge queue - this is the SOURCE OF TRUTH for pending merges.
 
 ```bash
-# Always fetch with prune to clean stale tracking refs:
 git fetch --prune origin
-
-# For each queued merge request, verify the branch exists:
-git branch -r | grep <branch>
-
-# IMPORTANT: Before queuing, verify branch has unmerged commits:
-git log origin/main..origin/<branch> --oneline | head -1
-# If empty → branch already merged. Archive MERGE_READY, don't queue.
+gt mq list <rig>
 ```
 
+The beads MQ tracks all pending merge requests. Do NOT rely on `git branch -r | grep polecat`
+as branches may exist without MR beads, or MR beads may exist for already-merged work.
+
 If queue empty, skip to context-check step.
 
-If branch doesn't exist for a queued item:
-- Mail witness: Branch not found, cannot merge
-- Remove from queue
+For each MR in the queue, verify the branch still exists:
+```bash
+git branch -r | grep <branch>
+```
 
-Track verified branch list for this cycle."""
+If branch doesn't exist for a queued MR:
+- Close the MR bead: `bd close <mr-id> --reason "Branch no longer exists"`
+- Remove from processing queue
+
+Track verified MR list for this cycle."""
 
 [[steps]]
 id = "process-branch"