Carousel buttons have the wrong or missing screen-reader label

• Where: carousel_previous.rb renders span.sr-only "Next slide";
  carousel_next.rb renders no sr-only span at all. Snapshot
  carousel/vertical line 17.
• Effect: a screen reader announces the previous button as "Next slide"
  and the next button as unlabeled.
• Fix: "Previous slide" on the previous button, add "Next slide" to the
  next button; re-record (on the 2.0 line) carousel/*.

Surfaced by the golden HTML suite (PR #536), which pins what 1.6 renders today — this defect included. Per maintainer decision (2026-09-19) main stays as is: this is addressed on the 2.0 line, and the golden snapshot that pins it is re-recorded there with the diff reviewed.

Source: design/v2/follow-up-issues.md.

Empieza con carousel_previous.rb y carousel_next.rb; después inspecciona el snapshot carousel/vertical de la línea 17 y los demás snapshots dorados de carousel/* en la línea 2.0. Ejecuta la suite de HTML dorado y vuelve a grabar carousel/*; se considera terminado cuando los botones anterior y siguiente tienen las etiquetas correctas para lectores de pantalla y el diff del snapshot revisado las refleja.