fix: Connect gt done and mq submit to refinery mrqueue (gt-9mzd)

Root cause: gt done and mq submit created merge-request beads but did
not write to the .beads/mq/ directory that the refinery Engineer
polls for work.

Changes:
- done.go: Submit to mrqueue after creating MR bead
- mq_submit.go: Submit to mrqueue after creating MR bead
- mq_migrate.go: New command to migrate existing stale MR beads
- mrqueue.go: Follow beads redirects for shared queue location

The migration command allows recovery of existing stale MRs that were
never processed because they only existed as beads.

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

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

internal/cmd/done.go

@@ -10,6 +10,7 @@ import (
 	"github.com/steveyegge/gastown/internal/events"
 	"github.com/steveyegge/gastown/internal/git"
 	"github.com/steveyegge/gastown/internal/mail"
+	"github.com/steveyegge/gastown/internal/mrqueue"
 	"github.com/steveyegge/gastown/internal/style"
 	"github.com/steveyegge/gastown/internal/workspace"
 )
@@ -163,6 +164,28 @@ func runDone(cmd *cobra.Command, args []string) error {
 		}
 		mrID = mrIssue.ID
 
+		// Also submit to mrqueue so refinery can process it
+		// The mrqueue is the work queue the refinery polls; beads are the audit record
+		mq, err := mrqueue.NewFromWorkdir(cwd)
+		if err != nil {
+			// Non-fatal: bead was created, just warn about queue
+			style.PrintWarning("could not access merge queue: %v", err)
+		} else {
+			mqEntry := &mrqueue.MR{
+				ID:          mrID,
+				Branch:      branch,
+				Target:      target,
+				SourceIssue: issueID,
+				Worker:      worker,
+				Rig:         rigName,
+				Title:       title,
+				Priority:    priority,
+			}
+			if err := mq.Submit(mqEntry); err != nil {
+				style.PrintWarning("could not submit to merge queue: %v", err)
+			}
+		}
+
 		// Success output
 		fmt.Printf("%s Work submitted to merge queue\n", style.Bold.Render("✓"))
 		fmt.Printf("  MR ID: %s\n", style.Bold.Render(mrID))