The OAuth callback was failing with "please_restart_the_process" because
Better-Auth's default DB-backed state (verification table) was unreliable —
the UAT hourly reset wipes all tables including verification records. Switch
to cookie-based state storage so the encrypted state survives in the browser
cookie across the redirect flow.
Also removes explicit redirectURI from socialProviders (Better-Auth derives
it from baseURL) and adds visible error feedback on the login page when
OAuth callbacks fail.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
Paperclip
085c8b9cfa