Supabase and Postgres security review for a live production app

I'm about to launch a community platform built on Lovable and Supabase. I need a scoped security review before launch, not general development work. Review every RLS policy across roughly 26 tables. Run a real attacker test using two accounts I provide, confirming one account genuinely cannot access another's data. Check for database constraints that don't match what the app code actually inserts, I've already found and fixed several. Review two flagged issues, users able to self-grant elevated privileges, and a Security Definer View, confirm if exploitable and fix. Review flagged dependency vulnerabilities and advise what's worth upgrading. Confirm a disposable email signup issue is properly closed. Need someone with real Postgres and Supabase RLS experience, please share specific examples. Fixed price preferred, quote against the scope above with your estimated turnaround.