Fix security vulnerability

supabase/migrations/20251026150444_b0a484eb-69c3-411e-8a0f-2f997b3e639e.sql

@@ -0,0 +1,3 @@
+-- Fix the security definer view by enabling security invoker mode
+-- This ensures the view respects RLS policies of the querying user
+ALTER VIEW public.petition_signatures_public SET (security_invoker = on);