refactor(convoy): replace SQLite queries with bd dep list commands

Replace direct sqlite3 CLI calls in getTrackedIssues and isTrackedByConvoy
with bd dep list commands that work with any beads backend (SQLite or Dolt).

- getTrackedIssues: Use bd dep list --direction=down --type=tracks --json
- isTrackedByConvoy: Use bd dep list --direction=up --type=tracks --json

This enables convoy commands to work with the Dolt backend.

Fixes: hq-e4eefc.2

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

internal/cmd/sling_convoy.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"crypto/rand"
 	"encoding/base32"
+	"encoding/json"
 	"fmt"
 	"os"
 	"os/exec"
@@ -29,32 +30,34 @@ func isTrackedByConvoy(beadID string) string {
 		return ""
 	}
 
-	// Query town beads for any convoy that tracks this issue
-	// Convoys use "tracks" dependency type: convoy -> tracked issue
-	townBeads := filepath.Join(townRoot, ".beads")
-	dbPath := filepath.Join(townBeads, "beads.db")
+	// Use bd dep list to find what tracks this issue (direction=up)
+	// Filter for open convoys in the results
+	depCmd := exec.Command("bd", "--no-daemon", "dep", "list", beadID, "--direction=up", "--type=tracks", "--json")
+	depCmd.Dir = townRoot
 
-	// Query dependencies where this bead is being tracked
-	// Also check for external reference format: external:rig:issue-id
-	query := fmt.Sprintf(`
-		SELECT d.issue_id
-		FROM dependencies d
-		JOIN issues i ON d.issue_id = i.id
-		WHERE d.type = 'tracks'
-		AND i.issue_type = 'convoy'
-		AND i.status = 'open'
-		AND (d.depends_on_id = '%s' OR d.depends_on_id LIKE '%%:%s')
-		LIMIT 1
-	`, beadID, beadID)
-
-	queryCmd := exec.Command("sqlite3", dbPath, query)
-	out, err := queryCmd.Output()
+	out, err := depCmd.Output()
 	if err != nil {
 		return ""
 	}
 
-	convoyID := strings.TrimSpace(string(out))
-	return convoyID
+	// Parse results and find an open convoy
+	var trackers []struct {
+		ID        string `json:"id"`
+		IssueType string `json:"issue_type"`
+		Status    string `json:"status"`
+	}
+	if err := json.Unmarshal(out, &trackers); err != nil {
+		return ""
+	}
+
+	// Return the first open convoy that tracks this issue
+	for _, tracker := range trackers {
+		if tracker.IssueType == "convoy" && tracker.Status == "open" {
+			return tracker.ID
+		}
+	}
+
+	return ""
 }
 
 // createAutoConvoy creates an auto-convoy for a single issue and tracks it.