/**
 * Compares two version strings for ordering.
 *
 * This function supports semantic versioning comparison (e.g., "1.0.0" vs "2.1.0")
 * and falls back to lexicographic comparison for non-semver strings.
 *
 * Rules:
 * - Empty/undefined versions are considered equal to each other
 * - An empty version is considered less than a non-empty version
 * - Semantic versions are compared numerically by component (major.minor.patch)
 * - Non-semantic versions are compared lexicographically (case-insensitive)
 *
 * @param sourceVersion - The first version to compare.
 * @param otherVersion - The second version to compare.
 * @returns A negative number if sourceVersion < otherVersion,
 *          zero if sourceVersion === otherVersion,
 *          a positive number if sourceVersion > otherVersion.
 *
 * @example
 * ```typescript
 * compareVersions("1.0.0", "2.0.0"); // Returns negative number
 * compareVersions("2.0.0", "1.0.0"); // Returns positive number
 * compareVersions("1.0.0", "1.0.0"); // Returns 0
 * compareVersions("", "1.0.0");      // Returns negative number
 * ```
 */
export declare function compareVersions(sourceVersion: string | undefined, otherVersion: string | undefined): number;