rohanislambd/fit-log-nextjs-app ? reverse-engineered prompt

Build me a modern workout planning app where people can browse a list of workouts, open any workout to see full details, and add exercises to a plan for today. I want a clean, responsive interface that looks good on mobile, tablet, and desktop, with a simple way to sort workouts and quickly find the right one.

The app should have a home page that shows workout cards with things like name, category, difficulty, duration, and rating. Each workout should have its own detail page with equipment, target muscle, instructions, and other useful info. There should also be a My Plan page where users can manage what they saved for later and what they want to do today.

Please make it feel polished, use toast messages for actions like saving or removing items, and keep the selected workouts saved even after refresh using local storage. Use current Next.js and Tailwind patterns, and look up anything you need online if it helps.