feat: implement Figlet, Pastel, and Unit tools with a unified layout

- Add Figlet text converter with font selection and history
- Add Pastel color palette generator and manipulation suite
- Add comprehensive Units converter with category-based logic
- Introduce AppShell with Sidebar and Header for navigation
- Modernize theme system with CSS variables and new animations
- Update project configuration and dependencies

components/pastel/color/PaletteGrid.tsx

@@ -0,0 +1,37 @@
+'use client';
+
+import { ColorSwatch } from './ColorSwatch';
+import { cn } from '@/lib/utils/cn';
+
+interface PaletteGridProps {
+  colors: string[];
+  onColorClick?: (color: string) => void;
+  className?: string;
+}
+
+export function PaletteGrid({ colors, onColorClick, className }: PaletteGridProps) {
+  if (colors.length === 0) {
+    return (
+      <div className="text-center py-12 text-muted-foreground">
+        No colors in palette yet
+      </div>
+    );
+  }
+
+  return (
+    <div
+      className={cn(
+        'grid grid-cols-3 sm:grid-cols-4 md:grid-cols-5 lg:grid-cols-6 gap-4',
+        className
+      )}
+    >
+      {colors.map((color, index) => (
+        <ColorSwatch
+          key={`${color}-${index}`}
+          color={color}
+          onClick={onColorClick ? () => onColorClick(color) : undefined}
+        />
+      ))}
+    </div>
+  );
+}