Refactor frontend components to utilize Mantine UI for improved consistency and usability

Commit notes

- Replaced Radix UI components with Mantine UI components across various frontend files, enhancing visual consistency. - Updated layout structures in components such as ADSRControls, Footer, and GainMeter for better responsiveness. - Refactored component styles and props to align with Mantine's design system, improving overall user experience. - Streamlined code by removing unused components and optimizing imports, contributing to a cleaner codebase.