Booking site for our wellness studio needs a real developer

We have a small chain of wellness studios and over the summer we put together a client booking site using Claude and Lovable. It runs on React with Supabase behind it and covers class schedules, memberships, instructor calendars and confirmation emails. Honestly it came out better than we expected, but we're not developers and we know the difference between a demo that works for us and a site our clients can rely on. What we need is someone experienced to look at what we have and take it the rest of the way. Logins are flaky, sometimes people get signed out mid-booking, and the password reset only works some of the time. We handle member payments and personal details, so we want someone to check that side carefully. And we'd like the code cleaned up enough that the next person who touches it isn't starting from scratch. We use OpenAI to write the class descriptions and a mail service for confirmations, so there are a couple of outside services wired in. Stack is React, Next.js, TypeScript, Node and Supabase. Tell us what you'd check first and roughly how you'd approach the first couple of weeks. If you've done this kind of cleanup on an AI-built app before, we'd like to hear about it. Likely more work after launch if it goes well.