Add square cover toggle and UI support

Introduce a SquareCoversToggle component and wire cover-aspect switching throughout the app. PreferencesContext now stores and persists a new squareCovers flag (with cross-tab sync), and pages (Home, Search) expose the toggle and pass the squareCovers prop to AudiobookGrid/AudiobookCard. AudiobookCard/Grid and skeletons were updated to respect square vs 2:3 aspect ratios and include smoother transitions. Also update app icons/manifest references to RMAB_1024x1024_ICON.png and make header/branding responsive (truncate titles, adjust version badge placement and logo usage). Minor UI/UX tweaks added for accessibility and visual polish.

public/manifest.json

@@ -8,7 +8,7 @@
   "theme_color": "#1e3a5f",
   "icons": [
     {
-      "src": "/RMAB_1024x1024.png",
+      "src": "/RMAB_1024x1024_ICON.png",
       "sizes": "1024x1024",
       "type": "image/png",
       "purpose": "any maskable"