fix: add DROP statements to supabase-setup.sql for clean reinstalls

TODO: Configure OAuth providers in Supabase dashboard:
- Google: Add Client ID and Secret from Google Cloud Console
- GitHub: Add Client ID and Secret from GitHub Developer Settings
- Set redirect URLs in Authentication → URL Configuration

supabase-setup.sql

@@ -1,6 +1,11 @@
 -- CODE CRISPIES - Supabase Database Setup
 -- Run this in Supabase Dashboard → SQL Editor → New Query
 
+-- Drop existing objects first
+  DROP FUNCTION IF EXISTS delete_own_account();
+  DROP TABLE IF EXISTS user_progress;
+  DROP TABLE IF EXISTS newsletter_subscribers;
+
 -- User progress table
 CREATE TABLE user_progress (
   id UUID PRIMARY KEY DEFAULT gen_random_uuid(),