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/figlet/constants/templates.ts

@@ -0,0 +1,38 @@
+export interface TextTemplate {
+  id: string;
+  label: string;
+  text: string;
+  category: 'greeting' | 'tech' | 'fun' | 'seasonal';
+}
+
+export const TEXT_TEMPLATES: TextTemplate[] = [
+  // Greetings
+  { id: 'hello', label: 'Hello', text: 'Hello!', category: 'greeting' },
+  { id: 'welcome', label: 'Welcome', text: 'Welcome', category: 'greeting' },
+  { id: 'hello-world', label: 'Hello World', text: 'Hello World', category: 'greeting' },
+
+  // Tech
+  { id: 'code', label: 'Code', text: 'CODE', category: 'tech' },
+  { id: 'dev', label: 'Developer', text: 'DEV', category: 'tech' },
+  { id: 'hack', label: 'Hack', text: 'HACK', category: 'tech' },
+  { id: 'terminal', label: 'Terminal', text: 'Terminal', category: 'tech' },
+  { id: 'git', label: 'Git', text: 'Git', category: 'tech' },
+
+  // Fun
+  { id: 'awesome', label: 'Awesome', text: 'AWESOME', category: 'fun' },
+  { id: 'cool', label: 'Cool', text: 'COOL', category: 'fun' },
+  { id: 'epic', label: 'Epic', text: 'EPIC', category: 'fun' },
+  { id: 'wow', label: 'Wow', text: 'WOW!', category: 'fun' },
+
+  // Seasonal
+  { id: 'happy-birthday', label: 'Happy Birthday', text: 'Happy Birthday!', category: 'seasonal' },
+  { id: 'congrats', label: 'Congrats', text: 'Congrats!', category: 'seasonal' },
+  { id: 'thanks', label: 'Thanks', text: 'Thanks!', category: 'seasonal' },
+];
+
+export const TEMPLATE_CATEGORIES = [
+  { id: 'greeting', label: 'Greetings', icon: '👋' },
+  { id: 'tech', label: 'Tech', icon: '💻' },
+  { id: 'fun', label: 'Fun', icon: '🎉' },
+  { id: 'seasonal', label: 'Seasonal', icon: '🎊' },
+] as const;