chore: remove keyboard navigation UI elements and related code

- Delete static/css/components/keyboard-nav.css entirely
- Remove @import of keyboard-nav.css from style.css
- Remove keyboard-nav-hint divs from controls.html and recipes.html
- Clean up all keyboard.* translation keys from 10 locale files

The actual keyboard scrolling handlers (PageUp/PageDown in infiniteScroll.js
and VirtualScroller.js) are kept as they provide core scroll functionality.

locales/de.json

@@ -1424,15 +1424,6 @@
             "duplicate": "Dieser Tag existiert bereits"
         }
     },
-    "keyboard": {
-        "navigation": "Tastatur-Navigation:",
-        "shortcuts": {
-            "pageUp": "Eine Seite nach oben scrollen",
-            "pageDown": "Eine Seite nach unten scrollen",
-            "home": "Zum Anfang springen",
-            "end": "Zum Ende springen"
-        }
-    },
     "initialization": {
         "title": "Initialisierung",
         "message": "Ihr Arbeitsbereich wird vorbereitet...",

locales/en.json

@@ -1424,15 +1424,6 @@
             "duplicate": "This tag already exists"
         }
     },
-    "keyboard": {
-        "navigation": "Keyboard Navigation:",
-        "shortcuts": {
-            "pageUp": "Scroll up one page",
-            "pageDown": "Scroll down one page",
-            "home": "Jump to top",
-            "end": "Jump to bottom"
-        }
-    },
     "initialization": {
         "title": "Initializing",
         "message": "Preparing your workspace...",

locales/es.json

@@ -1424,15 +1424,6 @@
             "duplicate": "Esta etiqueta ya existe"
         }
     },
-    "keyboard": {
-        "navigation": "Navegación por teclado:",
-        "shortcuts": {
-            "pageUp": "Desplazar hacia arriba una página",
-            "pageDown": "Desplazar hacia abajo una página",
-            "home": "Saltar al inicio",
-            "end": "Saltar al final"
-        }
-    },
     "initialization": {
         "title": "Inicializando",
         "message": "Preparando tu espacio de trabajo...",

locales/fr.json

@@ -1424,15 +1424,6 @@
             "duplicate": "Ce tag existe déjà"
         }
     },
-    "keyboard": {
-        "navigation": "Navigation au clavier :",
-        "shortcuts": {
-            "pageUp": "Défiler d'une page vers le haut",
-            "pageDown": "Défiler d'une page vers le bas",
-            "home": "Aller en haut",
-            "end": "Aller en bas"
-        }
-    },
     "initialization": {
         "title": "Initialisation",
         "message": "Préparation de votre espace de travail...",

locales/he.json

@@ -1424,15 +1424,6 @@
             "duplicate": "תגית זו כבר קיימת"
         }
     },
-    "keyboard": {
-        "navigation": "ניווט במקלדת:",
-        "shortcuts": {
-            "pageUp": "גלול עמוד אחד למעלה",
-            "pageDown": "גלול עמוד אחד למטה",
-            "home": "קפוץ להתחלה",
-            "end": "קפוץ לסוף"
-        }
-    },
     "initialization": {
         "title": "מאתחל",
         "message": "מכין את סביבת העבודה שלך...",

locales/ja.json

@@ -1424,15 +1424,6 @@
             "duplicate": "このタグは既に存在します"
         }
     },
-    "keyboard": {
-        "navigation": "キーボードナビゲーション：",
-        "shortcuts": {
-            "pageUp": "1ページ上にスクロール",
-            "pageDown": "1ページ下にスクロール",
-            "home": "トップにジャンプ",
-            "end": "ボトムにジャンプ"
-        }
-    },
     "initialization": {
         "title": "初期化中",
         "message": "ワークスペースを準備中...",

locales/ko.json

@@ -1424,15 +1424,6 @@
             "duplicate": "이 태그는 이미 존재합니다"
         }
     },
-    "keyboard": {
-        "navigation": "키보드 내비게이션:",
-        "shortcuts": {
-            "pageUp": "한 페이지 위로 스크롤",
-            "pageDown": "한 페이지 아래로 스크롤",
-            "home": "맨 위로 이동",
-            "end": "맨 아래로 이동"
-        }
-    },
     "initialization": {
         "title": "초기화 중",
         "message": "작업공간을 준비하고 있습니다...",

locales/ru.json

@@ -1424,15 +1424,6 @@
             "duplicate": "Этот тег уже существует"
         }
     },
-    "keyboard": {
-        "navigation": "Навигация с клавиатуры:",
-        "shortcuts": {
-            "pageUp": "Прокрутить на страницу вверх",
-            "pageDown": "Прокрутить на страницу вниз",
-            "home": "Перейти к началу",
-            "end": "Перейти к концу"
-        }
-    },
     "initialization": {
         "title": "Инициализация",
         "message": "Подготовка вашего рабочего пространства...",

locales/zh-CN.json

@@ -1424,15 +1424,6 @@
             "duplicate": "该标签已存在"
         }
     },
-    "keyboard": {
-        "navigation": "键盘导航：",
-        "shortcuts": {
-            "pageUp": "向上一页滚动",
-            "pageDown": "向下一页滚动",
-            "home": "跳到顶部",
-            "end": "跳到底部"
-        }
-    },
     "initialization": {
         "title": "初始化",
         "message": "正在准备你的工作空间...",

locales/zh-TW.json

@@ -1424,15 +1424,6 @@
             "duplicate": "此標籤已存在"
         }
     },
-    "keyboard": {
-        "navigation": "鍵盤導覽：",
-        "shortcuts": {
-            "pageUp": "向上捲動一頁",
-            "pageDown": "向下捲動一頁",
-            "home": "跳至頂部",
-            "end": "跳至底部"
-        }
-    },
     "initialization": {
         "title": "初始化",
         "message": "正在準備您的工作區...",