refactor: streamline toast system and harmonize UI across tools

- Migrate all toast notifications to sonner and remove custom ToastProvider
- Align Card and TextInput styling across Figlet and Pastel (rounded-lg, border-based)
- Fix build error by removing non-existent export in lib/units/index.ts
- Clean up unused Figlet components and constants

components/figlet/FontPreview.tsx

@@ -8,7 +8,7 @@ import { Skeleton } from '@/components/ui/Skeleton';
 import { EmptyState } from '@/components/ui/EmptyState';
 import { Copy, Download, Share2, Image as ImageIcon, AlignLeft, AlignCenter, AlignRight, Type } from 'lucide-react';
 import { cn } from '@/lib/utils/cn';
-import { useToast } from '@/components/ui/Toast';
+import { toast } from 'sonner';
 
 export interface FontPreviewProps {
   text: string;
@@ -28,7 +28,6 @@ export function FontPreview({ text, font, isLoading, onCopy, onDownload, onShare
   const previewRef = React.useRef<HTMLDivElement>(null);
   const [textAlign, setTextAlign] = React.useState<TextAlign>('left');
   const [fontSize, setFontSize] = React.useState<'xs' | 'sm' | 'base'>('sm');
-  const { addToast } = useToast();
 
   const handleExportPNG = async () => {
     if (!previewRef.current || !text) return;
@@ -44,10 +43,10 @@ export function FontPreview({ text, font, isLoading, onCopy, onDownload, onShare
       link.href = dataUrl;
       link.click();
 
-      addToast('Exported as PNG!', 'success');
+      toast.success('Exported as PNG!');
     } catch (error) {
       console.error('Failed to export PNG:', error);
-      addToast('Failed to export PNG', 'error');
+      toast.error('Failed to export PNG');
     }
   };
   return (