Supabase Auth Fix for HR App

I'm seeking an experienced developer to resolve several authentication issues in my HR/Payroll app that uses Supabase.

The following authentication flows are currently malfunctioning:
- Password reset
- Magic-link redirects
- Set-password step for invited users

We are also encountering a "signin is not a function" error on the frontend.

Ideal skills and experience:
- Strong knowledge of Supabase and its authentication mechanisms
- Experience with custom frontends, particularly those built on internal frameworks like Hostinger Horizon Builder
- Proficiency in debugging and fixing redirect/session errors
- Familiarity with password-based, magic link, and OAuth authentication flows