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.

carousel_previous.rb と carousel_next.rb から始め、次に 17 行目の snapshot carousel/vertical と、2.0 ラインにある他の carousel/* の golden snapshot を確認します。golden HTML suite を実行して carousel/* を再記録します。前へボタンと次へボタンに正しいスクリーンリーダー用ラベルが付き、確認済みの snapshot diff にそれらが反映されていれば完了です。