export function createStore(initial) {
  let state = { ...initial };
  const subscribers = new Set();

  return {
    get()           { return { ...state }; },
    set(updates)    { state = { ...state, ...updates }; subscribers.forEach(fn => fn(state)); },
    subscribe(fn)   { subscribers.add(fn); return () => subscribers.delete(fn); },
  };
}