Build a typing speed test called "TypeRace".
- Show a paragraph of text (random from 10 preset paragraphs)
- Real-time WPM calculation that updates every second
- Accuracy percentage
- Highlight: correct chars green, current char underline, errors red
- Timer: 30s, 60s, 120s modes
- Difficulty: Easy (common words), Medium (mixed), Hard (programming terms)
- Results screen: WPM, accuracy, time, errors count — with animated counter effect
- History: last 10 tests saved in localStorage with chart showing improvement
- Keyboard heatmap showing which keys had most errors
Design: clean centered layout, dark mode (#111), green accent (#10b981), monospace text display.