Adds "Reproducir carpeta" (sequential) and "Reproducir aleatorio"
(Fisher-Yates over the name-sorted order) as folder-scoped playable
actions, with auto-advance on track completion and skip next/prev.
Isolation from live radio is structural, not disciplinary: the
public playMediaItem always clears the local queue on any call, and
a new private _encolarCambioFuente is the only path that can advance
within it. _cambiarFuente, ControladorReconexion, and the reconnect
error path are untouched -- confirmed by a byte-for-byte empty diff
on all 4 pre-existing radio/reconnect regression suites, independently
re-run before and after (21/21 both times).
Handler wiring itself is static-review-only (PluriWaveAudioHandler
can't be unit-instantiated); the isolation/advance/race-guard
decision logic is extracted into cola_local.dart's pure functions,
which are fully unit-tested.
FreeTLab
dfd40ca937