1. Free project at supabase.com → Settings → API
2. Run this SQL once in the SQL Editor:

create table entries (
  id text primary key,
  user_id uuid references auth.users,
  type text, amount numeric, date text,
  description text, cat text, note text,
  created_at timestamptz default now()
);
create table categories (
  id serial primary key,
  user_id uuid references auth.users,
  entry_type text, name text, color text
);
alter table entries enable row level security;
alter table categories enable row level security;
create policy "own entries" on entries
  using (auth.uid() = user_id);
create policy "own categories" on categories
  using (auth.uid() = user_id);

3. Make sure Email auth is enabled in Authentication → Providers.