Symptom

When clicking "Add Set", the parent's onSetsChange callback receives an array that's always one set behind. The first click reports 0 sets, the second click reports 1 set, etc.

Expected

After clicking "Add Set", the parent should immediately receive the updated array including the new set.

What you know

This is a React component that manages a list of workout sets. When the user clicks "Add Set", the component should:

1. Add a new set to its internal state
2. Notify the parent of the updated set list via onSetsChange

The bug is in handleAddSet — the parent always receives a stale array.