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.

static/css/components/keyboard-nav.css

@@ -1,96 +0,0 @@
-/* Keyboard navigation indicator and help */
-.keyboard-nav-hint {
-    display: inline-flex;
-    align-items: center;
-    justify-content: center;
-    position: relative;
-    width: 32px;
-    height: 32px;
-    border-radius: 50%;
-    background: var(--card-bg);
-    border: 1px solid var(--border-color);
-    color: var(--text-color);
-    cursor: help;
-    transition: var(--transition-base);
-    margin-left: 8px;
-}
-
-.keyboard-nav-hint:hover {
-    background: var(--lora-accent);
-    color: white;
-    transform: translateY(-2px);
-    box-shadow: var(--shadow-sm);
-}
-
-.keyboard-nav-hint i {
-    font-size: 14px;
-}
-
-/* Tooltip styling */
-.tooltip {
-    position: relative;
-}
-
-.tooltip .tooltiptext {
-    visibility: hidden;
-    width: 240px;
-    background-color: var(--lora-surface);
-    color: var(--text-color);
-    text-align: center;
-    border-radius: var(--border-radius-xs);
-    padding: 8px;
-    position: absolute;
-    z-index: 9999; /* Ensure tooltip appears above cards */
-    right: 120%; /* Position tooltip to the left of the icon */
-    top: 50%; /* Vertically center */
-    transform: translateY(-15%); /* Vertically center */
-    opacity: 0;
-    transition: opacity 0.3s;
-    box-shadow: var(--shadow-lg);
-    border: 1px solid var(--lora-border);
-    font-size: 0.85em;
-    line-height: 1.4;
-}
-
-.tooltip .tooltiptext::after {
-    content: "";
-    position: absolute;
-    top: 50%; /* Vertically center arrow */
-    left: 100%; /* Arrow on the right side */
-    margin-top: -5px;
-    border-width: 5px;
-    border-style: solid;
-    border-color: transparent transparent transparent var(--lora-border); /* Arrow points right */
-}
-
-.tooltip:hover .tooltiptext {
-    visibility: visible;
-    opacity: 1;
-}
-
-/* Keyboard shortcuts table */
-.keyboard-shortcuts {
-    width: 100%;
-    border-collapse: collapse;
-    margin-top: 5px;
-}
-
-.keyboard-shortcuts td {
-    padding: 4px;
-    text-align: left;
-}
-
-.keyboard-shortcuts td:first-child {
-    font-weight: bold;
-    width: 40%;
-}
-
-.key {
-    display: inline-block;
-    background: var(--bg-color);
-    border: 1px solid var(--border-color);
-    border-radius: 3px;
-    padding: 1px 5px;
-    font-size: 0.8em;
-    box-shadow: var(--shadow-xs);
-}