/**
 * Safely read from localStorage.
 * - Returns undefined if not in browser
 * - Returns parsed JSON if value is JSON
 * - Returns plain string if not JSON
 * - Never throws
 */
export declare function readLocalStorage<T = unknown>(key: string): T | string | undefined;
/**
 * Safely write to localStorage.
 * - Automatically JSON.stringifies objects/arrays
 * - Stores plain strings as-is
 * - Never throws
 */
export declare function writeLocalStorage(key: string, value: unknown): void;
/**
 * Remove key safely
 */
export declare function removeLocalStorage(key: string): void;