totalPistas counted only DIRECT audio children, so "Reproducir carpeta"/
"Aleatorio" were hidden for a folder that contains only subfolders, and
playing a folder queued only its direct tracks.
Add a bounded recursive walk (pistasRecursivas) that collects every track
beneath a folder, depth-first, sorted by name at each level. Bounded on
two independent axes to keep a single tap's native SAF round-trips and
in-memory list size predictable on a deep or wide library:
- depth: 4 levels below the tapped folder (profundidadMaximaRecursivaLocal)
- count: 500 tracks total (limitePistasRecursivasLocal)
The folder-play/shuffle actions are now offered whenever the recursive
count is > 0, and "Reproducir carpeta"/"Aleatorio" queue everything found,
not just direct children.