[22/N] Add unit tests for AnimationMain

[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. 👉 #CURRENT — Add unit tests for AnimationMain (this PR)
23. ➡️ [23/N] Add unit tests for algo util helpers (PriorityQueue, SkipListHeads, GraphValues) #114 (Add unit tests for algo util helpers (PriorityQueue, SkipListHeads, GraphValues))

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Addresses #93

Context

Adds unit test coverage for AnimationMain.js, the core animation controller responsible for the animation loop, frame stepping, undo/history stacks, general animation controls, action dispatching (act.*), and algorithm-canvas coordination.

Changes Made

• Introduced src/anim/__tests__/AnimationMain.test.js covering:
• AnimationManager lifecycle, DOM control button binding (step forward/back, skip forward/back, play/pause), canvas sizing, and speed calculations.
• Math utilities (lerp), parsing routines (parseBool, parseColor), and timer controls (startTimer, stopTimer, timeout).
• Full animation state machine: startNewAnimation, sequential block stepping, pause/resume, stepBack, undoLastBlock, skipBack, and resetAll.
• The complete suite of action handlers (act.*) across node creation, text/label, dimensions, alignments, layer assignments, edge management, and incident edge removals on delete.
• Code line highlighting callbacks (highlightCodeLine, unhighlightCodeLine).
• Event callbacks (animStarted, animWaiting, animEnded, animUndoUnavailable) and status reporting.

Test Plan

• Ran npm test -- --watchAll=false
• Ran npm run lint and npm run prettier
• Verified >91% statement and line coverage on AnimationMain.js, completing test coverage across the entire src/anim/ package.