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/figlet/TextTemplates.tsx

@@ -0,0 +1,92 @@
+'use client';
+
+import * as React from 'react';
+import { Card } from '@/components/ui/Card';
+import { Button } from '@/components/ui/Button';
+import { Sparkles, ChevronDown, ChevronUp } from 'lucide-react';
+import { cn } from '@/lib/utils/cn';
+import { TEXT_TEMPLATES, TEMPLATE_CATEGORIES } from '@/lib/figlet/constants/templates';
+
+export interface TextTemplatesProps {
+  onSelectTemplate: (text: string) => void;
+  className?: string;
+}
+
+export function TextTemplates({ onSelectTemplate, className }: TextTemplatesProps) {
+  const [isExpanded, setIsExpanded] = React.useState(false);
+  const [selectedCategory, setSelectedCategory] = React.useState<string>('all');
+
+  const filteredTemplates = React.useMemo(() => {
+    if (selectedCategory === 'all') return TEXT_TEMPLATES;
+    return TEXT_TEMPLATES.filter(t => t.category === selectedCategory);
+  }, [selectedCategory]);
+
+  return (
+    <Card className={className}>
+      <div className="p-4">
+        <button
+          onClick={() => setIsExpanded(!isExpanded)}
+          className="w-full flex items-center justify-between text-sm font-medium hover:text-primary transition-colors"
+        >
+          <div className="flex items-center gap-2">
+            <Sparkles className="h-4 w-4" />
+            <span>Text Templates</span>
+            <span className="text-xs text-muted-foreground">({TEXT_TEMPLATES.length})</span>
+          </div>
+          {isExpanded ? (
+            <ChevronUp className="h-4 w-4" />
+          ) : (
+            <ChevronDown className="h-4 w-4" />
+          )}
+        </button>
+
+        {isExpanded && (
+          <div className="mt-4 space-y-3 slide-down">
+            {/* Category Filter */}
+            <div className="flex gap-1 flex-wrap">
+              <button
+                onClick={() => setSelectedCategory('all')}
+                className={cn(
+                  'px-2 py-1 text-xs rounded-md transition-colors',
+                  selectedCategory === 'all'
+                    ? 'bg-primary text-primary-foreground'
+                    : 'bg-muted hover:bg-muted/80'
+                )}
+              >
+                All
+              </button>
+              {TEMPLATE_CATEGORIES.map((cat) => (
+                <button
+                  key={cat.id}
+                  onClick={() => setSelectedCategory(cat.id)}
+                  className={cn(
+                    'px-2 py-1 text-xs rounded-md transition-colors',
+                    selectedCategory === cat.id
+                      ? 'bg-primary text-primary-foreground'
+                      : 'bg-muted hover:bg-muted/80'
+                  )}
+                >
+                  {cat.icon} {cat.label}
+                </button>
+              ))}
+            </div>
+
+            {/* Templates Grid */}
+            <div className="grid grid-cols-2 sm:grid-cols-3 gap-2">
+              {filteredTemplates.map((template) => (
+                <button
+                  key={template.id}
+                  onClick={() => onSelectTemplate(template.text)}
+                  className="px-3 py-2 text-xs bg-muted hover:bg-accent hover:scale-105 rounded-md transition-all text-left truncate"
+                  title={template.text}
+                >
+                  {template.label}
+                </button>
+              ))}
+            </div>
+          </div>
+        )}
+      </div>
+    </Card>
+  );
+}