Add interactive Vietnamese ML lesson on Perceptron fundamentals

[LMK89]

Summary

This PR introduces a comprehensive, interactive educational resource on Perceptron neural networks in Vietnamese. The lesson is delivered as a self-contained HTML file with embedded CSS and JavaScript, requiring no external dependencies or build process.

Key Changes

• New lesson file: 2026-08-20-perceptron-cd2c084e.html — A complete interactive tutorial covering:

  • Perceptron definition and mathematical formulation
  • Real-world problem: orange ripeness classification using two features (Brix sweetness, color)
  • Four distinct training states visualized with interactive plots showing decision boundaries
  • Live training demo where users can adjust learning rate and step through epochs
  • Prediction demo with step-by-step calculation display
  • Data quality guidance (normalization, label noise, class imbalance)
  • Practice exercises and self-grading quiz

• New README: Claude-lession/README.md — Documents the lesson series structure and naming convention (YYYY-MM-DD-<topic>-<random-hex>.html)

Implementation Details

• Responsive design: Uses CSS custom properties for theming with automatic dark mode support
• Canvas-based visualization: Decision boundary plots render dynamically based on model weights, showing correctly/incorrectly classified points
• Interactive training loop: Implements the perceptron learning algorithm in JavaScript with epoch-by-epoch visualization
• Data normalization: Includes z-score standardization to handle feature scaling issues
• Educational progression: Moves from theory → concrete example → visualization → hands-on interaction → reflection on limitations (XOR problem, linear separability)
• Accessibility: Semantic HTML, ARIA labels, keyboard navigation support, reduced-motion preferences respected

The lesson emphasizes practical understanding through visualization and interaction rather than pure theory, making it suitable for beginners new to neural networks.

https://claude.ai/code/session_01NDr1jZCzdzHU9MH6cNZKSc