Optimized navbar and sidebar for better performance and usability

[nikholas117]

Navbar: Reduced unnecessary re-renders by optimizing computed properties. Improved responsiveness by tweaking CSS classes and ensuring smooth layout adjustments across screen sizes. Sidebar: Enhanced mobile responsiveness with improved layout and interactions. Reduced excessive DOM manipulation by optimizing the use of Vue directives (v-for, v-if). These changes aim to improve the overall performance, maintainability, and user experience of the application, especially on mobile devices.