/**
 * Unflattens a flat object with dot notation keys into a nested object structure.
 *
 * @param obj - The flattened object to unflatten
 * @returns A nested object structure
 *
 * @example
 * ```ts
 * const flattened = {
 *   'user.profile.name': 'John',
 *   'user.profile.age': 30,
 *   'user.settings.theme': 'dark',
 *   'app.version': '1.0.0'
 * };
 *
 * const nested = unflattenObject(flattened);
 * // {
 * //   user: {
 * //     profile: {
 * //       name: 'John',
 * //       age: 30
 * //     },
 * //     settings: {
 * //       theme: 'dark'
 * //     }
 * //   },
 * //   app: {
 * //     version: '1.0.0'
 * //   }
 * // }
 * ```
 */
export declare function unflattenObject(obj: Record<string, any>): Record<string, any>;