chore: Add database migration scripts for username migration and hand…

…ling new users (#20)

supabase/migrations/20240626065103_migrate_username_from_email.sql

@@ -0,0 +1,4 @@
+UPDATE profiles AS p
+SET username = u.email
+FROM auth.users as u
+WHERE p.id = u.id AND p.username IS NULL;

supabase/migrations/20240626065226_update_handle_new_user.sql

@@ -0,0 +1,17 @@
+CREATE OR REPLACE FUNCTION public.handle_new_user()
+ RETURNS trigger
+ LANGUAGE plpgsql
+ SECURITY DEFINER
+AS $function$
+begin
+  insert into public.profiles (id, full_name, avatar_url, username)
+  values (
+    new.id, 
+    new.raw_user_meta_data->>'full_name', 
+    new.raw_user_meta_data->>'avatar_url',
+    new.email
+  );
+  return new;
+end;
+$function$
+;