migrate to better-auth

<img width="488" height="130" alt="Image" src="https://github.com/user-attachments/assets/57625a34-ceb9-4487-a64a-5e9937fc6f5c" />


This tool is not implemented yet, but the goal is to allow anyone currently using Clerk, Supabase, WorkOS, Auth0, or other authentication providers to easily automate migration to Better Auth using this tool as a dev tool.