[27/N] Add unit tests for Stack, Queue, and Deque algorithms (Array and LL variants)

[karkir0003]

🥞 Stack

1. ⬅️ [1/N] Update CI to run frontend unit tests #91 (Update CI to run frontend unit tests)
2. ⬅️ [2/N] Configure React Testing Library and Setup Tests #92 (Configure React Testing Library and Setup Tests)
3. ⬅️ [3/N] Add unit tests for SideButton component #94 (Add unit tests for SideButton component)
4. ⬅️ [4/N] Add unit tests for SearchFilter component #95 (Add unit tests for SearchFilter component)
5. ⬅️ [5/N] Add unit tests for Header and Footer components #96 (Add unit tests for Header and Footer components)
6. ⬅️ [6/N] Add unit tests for Blob mascot component #97 (Add unit tests for Blob mascot component)
7. ⬅️ [7/N] Add unit tests for AboutScreen screen #98 (Add unit tests for AboutScreen screen)
8. ⬅️ [8/N] Add integration tests for HomeScreen screen #99 (Add integration tests for HomeScreen screen)
9. ⬅️ [9/N] Add unit tests for AlgorithmNotFound404 component #100 (Add unit tests for AlgorithmNotFound404 component)
10. ⬅️ [10/N] Add integration tests for AlgoScreen screen #101 (Add integration tests for AlgoScreen screen)
11. ⬅️ [11/N] Add unit tests for ModalSidebarSectionTab component #102 (Add unit tests for ModalSidebarSectionTab component)
12. ⬅️ [12/N] Add unit tests for BigOModal component #103 (Add unit tests for BigOModal component)
13. ⬅️ [13/N] Add unit tests for Pseudocode component #104 (Add unit tests for Pseudocode component)
14. ⬅️ [14/N] Add unit and integration tests for AlgoSection component #105 (Add unit and integration tests for AlgoSection component)
15. ⬅️ [15/N] Add unit and integration tests for root App component #106 (Add unit and integration tests for root App component)
16. ⬅️ [16/N] Add unit tests for animation events and undo functions #107 (Add unit tests for animation events and undo functions)
17. ⬅️ [17/N] Add unit tests for AnimatedObject, AnimatedCircle, and AnimatedHighlightCircle #108 (Add unit tests for AnimatedObject, AnimatedCircle, and AnimatedHighlightCircle)
18. ⬅️ [18/N] Add unit tests for AnimatedRectangle, AnimatedLabel, and AnimatedLine #109 (Add unit tests for AnimatedRectangle, AnimatedLabel, and AnimatedLine)
19. ⬅️ [19/N] Add unit tests for AnimatedLinkedListNode, AnimatedDoublyLinkedListNode, and AnimatedCircularlyLinkedListNode #110 (Add unit tests for AnimatedLinkedListNode, AnimatedDoublyLinkedListNode, and AnimatedCircularlyLinkedListNode)
20. ⬅️ [20/N] Add unit tests for AnimatedBTreeNode and AnimatedSkipListNode #111 (Add unit tests for AnimatedBTreeNode and AnimatedSkipListNode)
21. ⬅️ [21/N] Add unit tests for ObjectManager #112 (Add unit tests for ObjectManager)
22. ⬅️ [22/N] Add unit tests for AnimationMain #113 (Add unit tests for AnimationMain)
23. ⬅️ [23/N] Add unit tests for algo util helpers (PriorityQueue, SkipListHeads, GraphValues) #114 (Add unit tests for algo util helpers (PriorityQueue, SkipListHeads, GraphValues))
24. ⬅️ [24/N] Add unit tests for base Algorithm class and control bar helpers #115 (Add unit tests for base Algorithm class and control bar helpers)
25. ⬅️ [25/N] Add unit tests for ArrayList algorithm #116 (Add unit tests for ArrayList algorithm)
26. ⬅️ [26/N] Add unit tests for LinkedList, DoublyLinkedList, and CircularlyLinkedList algorithms #117 (Add unit tests for LinkedList, DoublyLinkedList, and CircularlyLinkedList algorithms)
27. 👉 #CURRENT — Add unit tests for Stack, Queue, and Deque algorithms (Array and LL variants) (this PR)
28. ➡️ [28/N] Add unit tests for BST, AVL, Heap, and SplayTree algorithms #119 (Add unit tests for BST, AVL, Heap, and SplayTree algorithms)

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Addresses #93

Context

Adds comprehensive unit test coverage for the stack, queue, and deque algorithm visualizers across both array-backed and linked-list-backed implementations:
• StackArray.js: Array-backed stack with dynamic doubling resize.
• StackLL.js: Singly linked-list backed stack with Head pointer.
• QueueArray.js: Circular array-backed queue with modulo index wrap-around and unrolling resize.
• QueueLL.js: Linked-list backed queue with Head and Tail pointers.
• DequeArray.js: Double-ended circular array with front/back enqueue, dequeue, and shifted resize.
• DequeLL.js: Doubly linked-list backed deque with bidirectional Head and Tail manipulation.

Changes Made

• Introduced src/algo/__tests__/StackArray.test.js:
• Control registration (pushField, pushButton, popButton, randomButton, clearButton).
• push and pop operations, array doubling resize when full, capacity boundaries (MAX_SIZE), shaking invalid inputs.
• randomCallback, clearCallback, reset, and URL parameter deserialization (setURLData).

• Introduced src/algo/__tests__/StackLL.test.js:
• Linked list node instantiation, head pointer updates, and boundary shaking.
• Push to empty vs non-empty stack, pop multi-node vs single-node nullifying Head.
• randomCallback, clearAll, reset, and setURLData order verification.

• Introduced src/algo/__tests__/QueueArray.test.js:
• Circular array modulo indexing for enqueue ((front + size) % arraySize) and dequeue.
• Unrolling circular elements on dynamic doubling resize.
• Input validation, capacity limits, random generation, and parameter loading.

• Introduced src/algo/__tests__/QueueLL.test.js:
• Queue node linking with Head and Tail pointer maintenance.
• Dequeue operations handling single-element nullification and multi-element head advancement.
• Reset, clear, random routines, and URL data.

• Introduced src/algo/__tests__/DequeArray.test.js:
• Double-ended operations: addFirst, addLast, removeFirst, removeLast with circular modulo indexing.
• Specialized resize logic handling element shifting when expanding from front vs back.
• Edge cases (underflow shaking, empty inputs, capacity overflow), clear, and URL loading.

• Introduced src/algo/__tests__/DequeLL.test.js:
• Doubly linked list node creation, bidirectional pointer wiring (connectPrev/connectNext).
• Add/remove at front, back, and arbitrary index.
• Boundary handling (single-element deletion, empty deque checks), reset, clear, and URL parsing.

Test Plan

• Ran npm test -- --watchAll=false (all 6 new test suites pass, 86 unit tests passing).
• Ran npm run lint and npm run prettier (0 errors, 0 warnings).