Revert CORS allowed origin update for invoice-iq-gamma

[amar-295]

Problem

The backend CORS whitelist pointed to an old Vercel URL (invoiceiq-two.vercel.app)
that no longer matches the actual production frontend (invoice-iq-gamma.vercel.app).

This silently blocked every API call from production users — login, dashboard,
deliveries, and all other features were non-functional.

Fix

Updated allowedOrigins in backend/index.ts:

• 'https://invoiceiq-two.vercel.app'

• 'https://invoice-iq-gamma.vercel.app'

Impact

• ✅ Production API calls will work after backend redeploys
• ✅ Local dev unaffected (localhost:3000 still whitelisted)
• No schema, logic, or dependency changes

[Copilot]

Copilot wasn't able to review any files in this pull request.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[vercel]

@amar-295 is attempting to deploy a commit to the gurudas-bhardwaj's projects Team on Vercel.

A member of the Team first needs to authorize it.