fix(fonts): the app uses Inter again (#320)

Since the switch to @fontsource-variable/inter 5 (May), the package
registers the family 'Inter Variable', but the app still asked for the
4.x name 'InterVariable', so every user got their platform's default
sans-serif (Arial / Helvetica / DejaVu) and Settings → Appearance →
font "Inter" did nothing.

--font-secondary (index.css) and the App font map now ask for
'Inter Variable' first, keeping 'InterVariable' as a fallback for a
locally installed old version.

Verified headless: before, 0 Inter faces loaded and
document.fonts.check('16px "Inter Variable"') false; now the face loads
and the check is true.

Fixes #320

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/pages/App.tsx

@@ -48,7 +48,7 @@ import {
 const EMOJI_FONTS = 'var(--font-flags), var(--font-emoji)';
 const FONT_MAP: Record<string, string> = {
   system: `system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', ${EMOJI_FONTS}, sans-serif`,
-  inter: `'InterVariable', ${EMOJI_FONTS}, sans-serif`,
+  inter: `'Inter Variable', 'InterVariable', ${EMOJI_FONTS}, sans-serif`,
   'jetbrains-mono': `'JetBrains Mono', ${EMOJI_FONTS}, monospace`,
   'fira-code': `'Fira Code', ${EMOJI_FONTS}, monospace`,
 };

src/index.css

@@ -42,7 +42,8 @@
 
   --font-emoji: 'Twemoji_DISABLED';
   --font-flags: 'TwemojiFlags_DISABLED';
-  --font-secondary: 'InterVariable', var(--font-flags), var(--font-emoji), sans-serif;
+  --font-secondary:
+    'Inter Variable', 'InterVariable', var(--font-flags), var(--font-emoji), sans-serif;
 }
 
 .dark-theme,
@@ -66,7 +67,7 @@
   --mx-uc-7: hsl(243, 100%, 80%);
   --mx-uc-8: hsl(94, 100%, 80%);
 
-  --font-secondary: 'InterVariable', var(--font-emoji), sans-serif;
+  --font-secondary: 'Inter Variable', 'InterVariable', var(--font-emoji), sans-serif;
 }
 
 html {