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/utils/urlSharing.ts

@@ -0,0 +1,64 @@
+'use client';
+
+export interface ShareableState {
+  text: string;
+  font: string;
+}
+
+/**
+ * Encode text and font to URL parameters
+ */
+export function encodeToUrl(text: string, font: string): string {
+  const params = new URLSearchParams();
+
+  if (text) {
+    params.set('text', text);
+  }
+
+  if (font && font !== 'Standard') {
+    params.set('font', font);
+  }
+
+  const queryString = params.toString();
+  return queryString ? `?${queryString}` : '';
+}
+
+/**
+ * Decode URL parameters to get text and font
+ */
+export function decodeFromUrl(): ShareableState | null {
+  if (typeof window === 'undefined') return null;
+
+  const params = new URLSearchParams(window.location.search);
+  const text = params.get('text');
+  const font = params.get('font');
+
+  if (!text && !font) return null;
+
+  return {
+    text: text || '',
+    font: font || 'Standard',
+  };
+}
+
+/**
+ * Update the URL without reloading the page
+ */
+export function updateUrl(text: string, font: string): void {
+  if (typeof window === 'undefined') return;
+
+  const url = encodeToUrl(text, font);
+  const newUrl = url ? `${window.location.pathname}${url}` : window.location.pathname;
+
+  window.history.replaceState({}, '', newUrl);
+}
+
+/**
+ * Get shareable URL
+ */
+export function getShareableUrl(text: string, font: string): string {
+  if (typeof window === 'undefined') return '';
+
+  const query = encodeToUrl(text, font);
+  return `${window.location.origin}${window.location.pathname}${query}`;
+}