perf: self-host Google Fonts to eliminate render-blocking external request

Download Cormorant Garamond 600 and Manrope (variable, 400-800) woff2
files for latin + latin-ext subsets. Add @font-face declarations to
style.css and remove the Google Fonts <link> and preconnect hints from
base.html.

Eliminates the render-blocking CSS fetch to fonts.googleapis.com that
delayed First Contentful Paint by 100-300ms on typical connections.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>