Implement shuffle() and shuffled() methods for collections

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This PR adds two new methods to collections in the OOW library:

• shuffle() - Mutates the original array by shuffling its elements in place using the Fisher-Yates algorithm
• shuffled() - Returns a new shuffled copy without modifying the original collection

Usage Examples

// shuffle() - mutates the original array
const arr = [1, 2, 3, 4, 5];
arr.shuffle();
console.log(arr); // [3, 1, 5, 2, 4] (example output)

// shuffled() - returns new shuffled copy
const original = [1, 2, 3, 4, 5];
const shuffled = original.shuffled();
console.log(original); // [1, 2, 3, 4, 5] (unchanged)
console.log(shuffled); // [2, 5, 1, 3, 4] (example output)

// Works with strings too
const word = "hello";
const shuffledWord = word.shuffled();
console.log(word);         // "hello" (unchanged)
console.log(shuffledWord); // "llohe" (example output)

Implementation Details

• shuffle() is available only on Arrays (since it mutates the collection)
• shuffled() is available on both Arrays and Strings (via SequenceableCollection)
• Both methods handle edge cases like empty collections and single elements
• Uses the Fisher-Yates shuffle algorithm for uniform random distribution
• All existing tests continue to pass (129/129)
• Code passes linting without errors

Fixes #48.

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