MED-155: add RLS to public schema

supabase/migrations/20251007161700_enable_public_schema_rls.sql

@@ -0,0 +1,17 @@
+DO $$
+DECLARE
+  target_schema text := 'public';
+  table_name    text;
+BEGIN
+  FOR table_name IN
+    SELECT c.relname
+    FROM pg_class c
+    JOIN pg_namespace n ON n.oid = c.relnamespace
+    WHERE n.nspname = target_schema
+      AND c.relkind = 'r'
+  LOOP
+    EXECUTE format('ALTER TABLE %I.%I ENABLE ROW LEVEL SECURITY;', target_schema, table_name);
+  END LOOP;
+END $$;
+
+REVOKE USAGE ON SCHEMA public FROM anon, authenticated;