/**
 * Calculates a 1-based line number for a YAML key node using its range.
 *
 * Returns 0 when the range is missing or malformed.
 *
 * @param content - Original file content used to compute line breaks.
 * @param keyNode - YAML key node that may include a `range` tuple.
 * @returns 1-based line number, or 0 when unknown.
 */
export declare function getLineNumberForKey(content: string, keyNode: unknown): number;