Generate Random Unique ID

/**
 * Generate random unique ID
 * @param length ID length (default: 16)
 * @returns Random alphanumeric ID
 */
function generateRandomId(length = 16): string {
  const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  const array = new Uint8Array(length);
  crypto.getRandomValues(array);
  
  return Array.from(array, byte => chars[byte % chars.length]).join('');
}

// Usage Example
const userId = generateRandomId();
const shortId = generateRandomId(8);
console.log(userId); // e.g., '78a9s7d89k2m87s9'
console.log(shortId); // e.g., '89s7d89k'