/**
 * rill list: Display all installed extension mounts.
 *
 * Constraints (FR-EXT-7, UXI-EXT-7, UXT-EXT-12):
 * - Pre-check: rill-config.json exists (EC-22)
 * - --json mode: also requires .rill/npm/package.json (EC-23)
 * - Output rows equal Object.keys(extensions.mounts).length (NFR-EXT-8)
 * - File I/O < 500ms (NFR-EXT-4)
 */
/**
 * List all extension mounts from rill-config.json.
 *
 * Implements FR-EXT-7, UXT-EXT-12, UXI-EXT-7, EC-22..EC-25.
 */
export declare function run(argv: string[]): Promise<number>;