fix: address code review issues on PR #9

- gofmt main.go to fix tab indentation in main() body
- stats.go ComputeSummary: return nil when Answers and ByType are empty
- dns/types.go: remove duplicate ParseQueryType (dead code)
- formatter.go: log hook errors to stderr when Debug > 0; add Debug to Config
- text.go referralID: remove redundant depth==0 branch
- text.go writeServers: remove version lookup placeholder string

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: multica-agent <github@multica.ai>

internal/output/text.go

@@ -99,11 +99,7 @@ func (f *textFormatter) writeServers(results []traverse.TraversalResult) error {
 
 	for _, name := range names {
 		for _, ip := range servers[name] {
-			version := ""
-			if f.cfg.ShowVersions {
-				version = " (version lookup pending)"
-			}
-			if _, err := fmt.Fprintf(f.w, "%*s: %-15s%s\n", width, name, ip, version); err != nil {
+			if _, err := fmt.Fprintf(f.w, "%*s: %-15s\n", width, name, ip); err != nil {
 				return err
 			}
 		}
@@ -234,9 +230,6 @@ func referralID(ref *traverse.Referral) string {
 	if ref == nil {
 		return ""
 	}
-	if ref.Depth == 0 {
-		return "1"
-	}
 	return fmt.Sprintf("%d", ref.Depth+1)
 }