Replaces the screenshot placeholder with a live animated demo showing:
- Sidebar with fake sessions and token usage bars
- User typing animation with cursor
- Thinking indicator with animated dots
- Colored tool call badges (web_search, exec)
- Expandable tool results with parameters
- Formatted assistant response with markdown
- Auto-looping animation
All pure CSS/JS, no dependencies. Matches the app's dark theme and color scheme.
Closes feedback item #12
d26c4988f2