feat(convoy): add epic filtering flags to convoy list

Add three new flags for filtering convoys by epic relationship:
- --orphans: show only convoys without a parent epic
- --epic <id>: show only convoys under a specific epic
- --by-epic: group convoys by parent epic

These support the Goals Layer feature (Phase 3) for hierarchical
focus management.

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

internal/cmd/convoy.go

@@ -1260,6 +1260,7 @@ func runConvoyList(cmd *cobra.Command, args []string) error {
 		convoys = filtered
 	}
 
+
 	if convoyListJSON {
 		enc := json.NewEncoder(os.Stdout)
 		enc.SetIndent("", "  ")
@@ -1394,59 +1395,38 @@ func printConvoyTreeFromItems(townBeads string, convoys []convoyListItem) error
 	return nil
 }
 
-// printConvoyTree displays convoys with their child issues in a tree format.
-func printConvoyTree(townBeads string, convoys []struct {
-	ID        string `json:"id"`
-	Title     string `json:"title"`
-	Status    string `json:"status"`
-	CreatedAt string `json:"created_at"`
-}) error {
-	for _, c := range convoys {
-		// Get tracked issues for this convoy
-		tracked := getTrackedIssues(townBeads, c.ID)
-
-		// Count completed
-		completed := 0
-		for _, t := range tracked {
-			if t.Status == "closed" {
-				completed++
-			}
-		}
-
-		// Print convoy header with progress
-		total := len(tracked)
-		progress := ""
-		if total > 0 {
-			progress = fmt.Sprintf(" (%d/%d)", completed, total)
-		}
-		fmt.Printf("🚚 %s: %s%s\n", c.ID, c.Title, progress)
-
-		// Print tracked issues as tree children
-		for i, t := range tracked {
-			// Determine tree connector
-			isLast := i == len(tracked)-1
-			connector := "├──"
-			if isLast {
-				connector = "└──"
-			}
-
-			// Status symbol: ✓ closed, ▶ in_progress/hooked, ○ other
-			status := "○"
-			switch t.Status {
-			case "closed":
-				status = "✓"
-			case "in_progress", "hooked":
-				status = "▶"
-			}
-
-			fmt.Printf("%s %s %s: %s\n", connector, status, t.ID, t.Title)
-		}
-
-		// Add blank line between convoys
-		fmt.Println()
+// getEpicTitles fetches titles for the given epic IDs.
+func getEpicTitles(epicIDs []string) map[string]string {
+	result := make(map[string]string)
+	if len(epicIDs) == 0 {
+		return result
 	}
 
-	return nil
+	// Use bd show to get epic details (handles routing automatically)
+	args := append([]string{"show"}, epicIDs...)
+	args = append(args, "--json")
+
+	showCmd := exec.Command("bd", args...)
+	var stdout bytes.Buffer
+	showCmd.Stdout = &stdout
+
+	if err := showCmd.Run(); err != nil {
+		return result
+	}
+
+	var issues []struct {
+		ID    string `json:"id"`
+		Title string `json:"title"`
+	}
+	if err := json.Unmarshal(stdout.Bytes(), &issues); err != nil {
+		return result
+	}
+
+	for _, issue := range issues {
+		result[issue.ID] = issue.Title
+	}
+
+	return result
 }
 
 func formatConvoyStatus(status string) string {
@@ -1462,6 +1442,61 @@ func formatConvoyStatus(status string) string {
 	}
 }
 
+// getConvoyParentEpics returns a map from convoy ID to parent epic ID.
+// Convoys link to epics via child_of dependency type.
+// Uses a single batched query for efficiency.
+func getConvoyParentEpics(townBeads string, convoyIDs []string) map[string]string {
+	result := make(map[string]string)
+	if len(convoyIDs) == 0 {
+		return result
+	}
+
+	dbPath := filepath.Join(townBeads, "beads.db")
+
+	// Build IN clause with properly escaped IDs
+	var quotedIDs []string
+	for _, id := range convoyIDs {
+		safeID := strings.ReplaceAll(id, "'", "''")
+		quotedIDs = append(quotedIDs, fmt.Sprintf("'%s'", safeID))
+	}
+	inClause := strings.Join(quotedIDs, ", ")
+
+	// Query child_of dependencies for all convoys at once
+	query := fmt.Sprintf(
+		`SELECT issue_id, depends_on_id FROM dependencies WHERE issue_id IN (%s) AND type = 'child_of'`,
+		inClause)
+
+	queryCmd := exec.Command("sqlite3", "-json", dbPath, query)
+	var stdout bytes.Buffer
+	queryCmd.Stdout = &stdout
+
+	if err := queryCmd.Run(); err != nil {
+		return result
+	}
+
+	var deps []struct {
+		IssueID     string `json:"issue_id"`
+		DependsOnID string `json:"depends_on_id"`
+	}
+	if err := json.Unmarshal(stdout.Bytes(), &deps); err != nil {
+		return result
+	}
+
+	for _, dep := range deps {
+		epicID := dep.DependsOnID
+		// Handle external reference format: external:rig:issue-id
+		if strings.HasPrefix(epicID, "external:") {
+			parts := strings.SplitN(epicID, ":", 3)
+			if len(parts) == 3 {
+				epicID = parts[2] // Extract the actual issue ID
+			}
+		}
+		result[dep.IssueID] = epicID
+	}
+
+	return result
+}
+
 // trackedIssueInfo holds info about an issue being tracked by a convoy.
 type trackedIssueInfo struct {
 	ID        string `json:"id"`