Build a small analytics helper — each step uses a different foundation:
1. Write average(numbers) that RETURNS the mean of an array of numbers (empty array returns 0).
2. Write formatScore(name, score) that RETURNS a template-literal sentence like "Ada scored 91".
3. Write bestLearner(learners) that takes an array of { name, score } objects and RETURNS the whole object with the highest score.
4. checkReady() is provided — it returns a promise resolving to true. Write an async function announce() that awaits it and returns the string "ready" when true.
Difficulty: intermediate