Major changes:
- Upgrade Tailwind CSS from v3 to v4 with @tailwindcss/postcss
- Remove deprecated Tailwind v3 configuration and PostCSS plugins
- Upgrade Zod from v3 to v4
- Update React Markdown and other dependencies to latest versions
- Remove @plaiceholder, @headlessui, and other unused dependencies
- Replace SCSS with standard CSS globals
- Add font packages (@fontsource-variable) for better typography
- Consolidate Prettier configuration to .prettierrc
- Remove legacy contact page and custom Payload SCSS
- Add Mantine hooks and Lucide React for improved UI components
