AI Opponent added

[TheRaj71]

This pull request enhances the tic-tac-toe game by adding new features and improving existing functionality. The most important changes include adding AI mode, restructuring the event listeners, and refactoring the game logic for better readability and maintainability.

New Features

• Added AI mode to allow players to play against the computer. (js/script.js js/script.jsL18-L117)
• Introduced a mode selection dropdown to switch between multiplayer and AI mode. (js/script.js js/script.jsL18-L117)

Event Listeners

• Refactored event listeners for sound toggle and game reset into separate functions. (js/script.js js/script.jsL18-L117)

Game Logic

• Refactored the handleCellClick function to incorporate AI moves and end game conditions. (js/script.js js/script.jsL18-L117)
• Added makeMove, makeAIMove, findBestMove, and minimax functions to handle AI decision-making. (js/script.js js/script.jsL18-L117)

Code Cleanup

• Improved readability by restructuring the checkWinner and isBoardFull functions. (js/script.js [1] [2]
• Consolidated repeated code into helper functions and removed unnecessary comments. (js/script.js [1] [2]

[arujjval]

Mention the issue it is resolving.

[TheRaj71]

Mention the issue it is resolving.

Issue 26 (user can siwtch between multiplayer and ai mode)

[arujjval]

please make this PR to development branch.