Fix (JavaScript) selectionSort example mutating the input array

[stanislaw-grin]

Summary

This PR fixes a small issue in the selectionSort implementation from the JavaScript examples.

The current implementation uses Array.prototype.splice() directly on the input array, which mutates the original array. As a result, the source array becomes empty after sorting, which is likely unintended behavior — especially in educational material.

What was changed

• Created a shallow copy of the input array using the spread syntax ([...arr]) to avoid mutating the original.
• Preserved the original logic for clarity and consistency with the rest of the examples.

Before

const sourceArray = [5, 3, 6, 2, 10];
const sortedArray = selectionSort(sourceArray);
console.log(sourceArray); // []

After

const sourceArray = [5, 3, 6, 2, 10];
const sortedArray = selectionSort(sourceArray);
console.log(sourceArray); // [5, 3, 6, 2, 10]