Implement a Queue using Stack

A queue is a First-In-First-Out (FIFO) data structure. In this problem, you are to simulate a queue using only stacks (which are Last-In-First-Out, LIFO). Your task is to implement the enqueue, dequeue, and peek methods using stack operations.

• enqueue(value) → Adds an element to the end of the queue.
• dequeue() → Removes and returns the element from the front of the queue.
• peek() → Returns the element at the front without removing it.
• isEmpty() → Returns true if the queue is empty, else false.

Example Inputs & Outputs

const q = new QueueUsingStack();
q.enqueue(1);
q.enqueue(2);
q.enqueue(3);
q.dequeue();     // Output: 1
q.peek();        // Output: 2
q.isEmpty();     // Output: false

Constraints & Edge Cases

• Only standard stack operations (push, pop, peek, length) are allowed.
• All operations should have amortized O(1) time complexity.
• Calling dequeue or peek on an empty queue should throw an error or return a clear indicator like null.
• Support both integer and string data types as queue elements.