Fix the replay that counts leaked resize listeners

A responsive layout hook adds a resize listener in an effect with an empty dependency list, and returns no cleanup. After a few page changes the app slows down, and the team wants a replay that counts the listeners still registered.

An assistant wrote active_listener_count(lifecycle_events, has_cleanup). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• lifecycle_events: the component's lifecycle events, in order, such as "mount", "unmount" and "rerender". A recording can start after the component mounted.
• has_cleanup: true when the effect returns a teardown function that removes the listener, false when it returns nothing.
• Return the number of listeners still registered at the end, as an integer.

Rules the tests check:

• Start with 0 listeners.
• "mount": the effect runs and adds 1 listener.
• "unmount": when has_cleanup is true, the teardown removes 1 listener. When it is false, nothing is removed.
• An "unmount" when no listener is registered removes nothing. The count never goes below 0.
• Any other event, such as "rerender", changes nothing. An effect with an empty dependency list runs once per mount, not once per render.
• Event names are case sensitive, so "MOUNT" changes nothing.
• No events returns 0.