perf(fonts): convert Lato fonts from TTF to WOFF2

- Replace 12 TTF files with WOFF2 equivalents (1.9MB -> 700KB)
- Add font-face declarations for Thin (weight 100) normal and italic
- Update fonts.css to reference .woff2 with format('woff2')

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jaysin586