feat: Add "Evolution of Large Model Data Engineering" post and enable MathJax

[modernchina123]

This PR adds a new research article titled "Evolution of Large Model Data Engineering" and introduces necessary technical improvements to support mathematical content and better reading experience.

✨ Key Changes

📄 Content

• New Post: Added 2026-01-14-evolution-of-large-model-data-engineering.... This deep-dive article discusses the shift from data quantity to knowledge density in AGI development.
• Assets: Included 20+ diagrams and figures in assets/Sky/.
• New Author: Added Sky (Data Scientist) to _data/authors.yml.

🔧 Technical Improvements

• Math Support: Enabled MathJax in _includes/head.html to properly render mathematical formulas (e.g., Scaling Laws equations).
• UI/UX Refinements:
  • Improved CSS for better font rendering and hidden scrollbars.
  • Fixed long URL overflows in figure captions.
  • Updated footer to use dynamic year generation.

🔍 Verification

• Verified that the new post renders correctly with all images.
• Verified that mathematical formulas (LaTeX) satisfy the rendering requirements.
• Validated that the new author "Sky" appears correctly in metadata.