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

lib/pastel/utils/export.ts

@@ -0,0 +1,83 @@
+/**
+ * Export utilities for color palettes
+ */
+
+export interface ExportColor {
+  name?: string;
+  hex: string;
+}
+
+/**
+ * Export colors as CSS variables
+ */
+export function exportAsCSS(colors: ExportColor[]): string {
+  const variables = colors
+    .map((color, index) => {
+      const name = color.name || `color-${index + 1}`;
+      return `  --${name}: ${color.hex};`;
+    })
+    .join('\n');
+
+  return `:root {\n${variables}\n}`;
+}
+
+/**
+ * Export colors as SCSS variables
+ */
+export function exportAsSCSS(colors: ExportColor[]): string {
+  return colors
+    .map((color, index) => {
+      const name = color.name || `color-${index + 1}`;
+      return `$${name}: ${color.hex};`;
+    })
+    .join('\n');
+}
+
+/**
+ * Export colors as Tailwind config
+ */
+export function exportAsTailwind(colors: ExportColor[]): string {
+  const colorEntries = colors
+    .map((color, index) => {
+      const name = color.name || `color-${index + 1}`;
+      return `        '${name}': '${color.hex}',`;
+    })
+    .join('\n');
+
+  return `module.exports = {\n  theme: {\n    extend: {\n      colors: {\n${colorEntries}\n      },\n    },\n  },\n};`;
+}
+
+/**
+ * Export colors as JSON
+ */
+export function exportAsJSON(colors: ExportColor[]): string {
+  const colorObjects = colors.map((color, index) => ({
+    name: color.name || `color-${index + 1}`,
+    hex: color.hex,
+  }));
+
+  return JSON.stringify({ colors: colorObjects }, null, 2);
+}
+
+/**
+ * Export colors as JavaScript array
+ */
+export function exportAsJavaScript(colors: ExportColor[]): string {
+  const colorArray = colors.map((c) => `'${c.hex}'`).join(', ');
+  return `const colors = [${colorArray}];`;
+}
+
+/**
+ * Download text as file
+ */
+export function downloadAsFile(content: string, filename: string, mimeType: string = 'text/plain') {
+  const blob = new Blob([content], { type: mimeType });
+  const url = URL.createObjectURL(blob);
+  const link = document.createElement('a');
+  link.href = url;
+  link.download = filename;
+  document.body.appendChild(link);
+  link.click();
+  document.body.removeChild(link);
+  URL.revokeObjectURL(url);
+}