feat(ui): Components refactoring with Tailwind - UI kit, icons, lazy loading images

- Created reusable UI components (Card, Button, Badge, Form, Icon)
- Added PageIcon and NavIcon components with consistent styling
- Refactored all pages to use new UI components
- Added non-blocking image loading with skeleton for book covers
- Created LibraryActions dropdown for library settings
- Added emojis to buttons for better UX
- Fixed Client Component issues with getBookCoverUrl

apps/backoffice/app/components/ui/Card.tsx

@@ -0,0 +1,27 @@
+import { ReactNode } from "react";
+
+interface CardProps {
+  children: ReactNode;
+  className?: string;
+}
+
+export function Card({ children, className = "" }: CardProps) {
+  return (
+    <div className={`bg-card rounded-xl shadow-soft border border-line p-6 ${className}`}>
+      {children}
+    </div>
+  );
+}
+
+interface CardHeaderProps {
+  title: string;
+  className?: string;
+}
+
+export function CardHeader({ title, className = "" }: CardHeaderProps) {
+  return (
+    <h2 className={`text-lg font-semibold text-foreground mb-4 ${className}`}>
+      {title}
+    </h2>
+  );
+}