feat(showcase): add wheel, swipe and keyboard navigation to the example gallery

- Wheel on the main viewer: horizontal deltas always switch examples;
  vertical deltas switch only at the modal scroll boundary, then stay in a
  sticky session (down = next, up = prev) until the pointer leaves the area
- Touch/pen horizontal swipe switches examples; the synthesized click after
  a swipe is swallowed so the media viewer does not open
- '[' / ']' switch examples while the gallery is expanded; ArrowLeft/Right
  stay reserved for model-level navigation
- Direction-aware slide transition on every switch for visual feedback
  (respects prefers-reduced-motion)

locales/ko.json

@@ -1664,8 +1664,8 @@
                 "showCount": "예시 보기 ({count})",
                 "hideExamples": "예시 숨기기",
                 "addExamples": "예시 추가",
-                "previousExample": "이전 예시",
-                "nextExample": "다음 예시",
+                "previousExample": "이전 예시([)",
+                "nextExample": "다음 예시(])",
                 "noExamples": "사용 가능한 예시 이미지가 없습니다",
                 "addMoreExamples": "예시 더 추가",
                 "dragDrop": "이미지 또는 비디오를 여기로 끌어다 놓으세요",