Refactor admin blog access

supabase/migrations/20251010230214_addcca80-9fb4-4f5a-b581-34463dec5c47.sql

@@ -0,0 +1,10 @@
+-- Drop existing policy that allows moderators
+DROP POLICY IF EXISTS "Admins can do everything" ON public.blog_posts;
+
+-- Create new policy for admins and superusers only
+CREATE POLICY "Admins and superusers can manage blog posts"
+  ON public.blog_posts FOR ALL
+  USING (
+    has_role(auth.uid(), 'admin'::app_role) OR 
+    has_role(auth.uid(), 'superuser'::app_role)
+  );