Next.js JS-to-TS Responsive Upgrade

I have an existing Next.js application written in plain JavaScript that I now need fully migrated to TypeScript. During the conversion I also want the codebase tightened up with stronger form validation and cleaner state management so the end result is both safer and easier to maintain.

Key points I care about:
• Every page and component moved to TypeScript with meaningful types, no any fallbacks.
• Modern, scalable state handling (Redux Toolkit, Zustand, or a comparable approach) replacing the scattered local state now in use.
• Robust form validation—Formik, React-Hook-Form, or similar—wired to surface clear, accessible error messages.
• While refactoring, make the UI genuinely responsive at all breakpoints; the current CSS works but feels brittle on smaller screens.

I’ll grant you access to the Git repository so you can work branch-by-branch. The deliverable is a clean pull request that compiles with strict mode enabled, passes linting, and renders identically (or better) across mobile, tablet, and desktop.

If this sounds straightforward and you have proven TypeScript experience with Next.js, I’m happy to jump on a quick call, walk you through the repo, and get started right away.