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/ui/Button.tsx

@@ -19,7 +19,7 @@ const Button = React.forwardRef<HTMLButtonElement, ButtonProps>(
           {
             'bg-primary text-primary-foreground shadow-[0_0_20px_rgba(139,92,246,0.3)] hover:bg-primary/90 hover:shadow-[0_0_25px_rgba(139,92,246,0.5)] hover:-translate-y-0.5':
               variant === 'default',
-            'glass bg-white/5 border-white/10 hover:bg-white/10 hover:border-white/20 text-foreground':
+            'glass hover:bg-accent/10 hover:border-primary/20 text-foreground':
               variant === 'outline',
             'hover:bg-accent hover:text-accent-foreground': variant === 'ghost',
             'bg-destructive text-destructive-foreground hover:bg-destructive/90 shadow-lg hover:shadow-destructive/20':