73b046f7a2
The legacy ``@fontsource/geist-sans`` (v5.2.5) ships latin only and
``@fontsource/geist-mono`` was imported with the default subset only —
so Russian text in the sidebar (nav links, section labels, badges) fell
back to system fonts (Segoe UI / Cascadia / Consolas) and visibly
clashed with the Latin glyphs around it.
- Switched the sans family to ``@fontsource-variable/geist`` (single
variable woff2 with latin + latin-ext + cyrillic). Updated
``--font-sans`` to lead with ``'Geist Variable'`` then keep the old
``'Geist Sans'`` and system fallbacks for safety.
- Added ``@fontsource/geist-mono/cyrillic-{400,500,600}.css`` imports
so Geist Mono renders Russian glyphs in the section labels and
monospace badges instead of falling back.
Newsreader (display serif) still has no Cyrillic on fontsource, so
italic page-hero emphasis in Russian still falls back to Georgia.
That's a separate, less-prominent concern and a future swap.