Feat/UI upgrade

[daipham3213]

This pull request introduces significant updates to the project, including a complete overhaul of the index.html structure, the addition of a modular CSS architecture, and the removal of unused JavaScript code. These changes aim to modernize the UI, improve maintainability, and enhance the user experience.

HTML Updates:

• Rewrote index.html to include semantic improvements, a modernized structure, and updated meta tags for SEO. Added a macOS-style terminal UI with new header, footer, and main content sections.

CSS Architecture:

• Introduced a modular CSS structure with separate files for base styles, layout, modules, state, and theme. Key additions include foundational styles (_base.css), layout adjustments (_layout.css), and module-specific styles like terminal-window.css and footer-stats.css. [1] [2] [3] [4]
• Added theme-specific styles, including a spinning border effect for interactive elements (spinning-border.css). [1] [2]

JavaScript Cleanup:

• Removed the main.js file, which contained outdated and unused emulator initialization logic. This eliminates redundant code and prepares the project for a more modular JavaScript implementation.

ESLint Configuration:

• Updated .eslintrc.json to enforce stricter rules by enabling the no-bitwise rule with exceptions for certain operators. This ensures cleaner and more maintainable code.