Add migration to revoke PUBLIC access on new tables

REVOKE statements are not captured by supabase db diff (known limitation
of migra tool). Adding separate migration as recommended by Supabase docs.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: justanotheratom

supabase/migrations/20251218113156_revoke_public_access_new_tables.sql

@@ -0,0 +1,6 @@
+-- Revoke default PUBLIC access on new tables.
+-- REVOKE statements are not captured by supabase db diff, so we add them manually.
+-- See: https://supabase.com/docs/guides/local-development/declarative-database-schemas
+
+REVOKE ALL ON TABLE public.feedback FROM PUBLIC;
+REVOKE ALL ON TABLE public.scan_analyses FROM PUBLIC;