Toast Notification Stack with Queue

Create a toast notification system with:
- Toast appears in the bottom-right corner
- 4 types: success (green), error (red), warning (yellow), info (blue)
- Each toast: icon, title, description, dismiss X button
- Auto-dismisses after 4 seconds with a shrinking progress bar
- Multiple toasts stack vertically with newest on top
- Hover pauses the auto-dismiss timer
- Smooth slide-in from right, slide-out to right
- Maximum 3 toasts visible, older ones queued
- Demo buttons to trigger each toast type
- Use shadcn/ui, Tailwind CSS