fix(lint): check strings.Builder WriteString return value (errcheck)

backend/internal/service/openai_codex_transform.go

@@ -1176,7 +1176,7 @@ func extractLosslessTextFromContent(content any) (string, bool) {
 			if !ok {
 				return "", false
 			}
-			b.WriteString(text)
+			_, _ = b.WriteString(text)
 		}
 		return b.String(), true
 	default: