fix: remove auth0Routes() as it is incompatible with React Router file-based route config

[yogeshchoudhary147]

Problem

auth0Routes() returned inline route objects with loader/action functions. React Router's RouteConfig only accepts { path, file } entries at build time and rejects anything else with:

Invalid key: Expected 'file' but received undefined

Fix

• Removed auth0Routes() from handlers.ts and its exports from server/index.ts
• Replaced the routes/index.ts re-export with a comment documenting the correct pattern using a splat route file (auth.$.tsx) with handleAuth