feat: Inter font, weight 450, bumped base sizes across all pages

- Load Inter variable font from Google Fonts on all 5 HTML pages
- font-weight: 450 on body (between regular and medium — fixes thin feel)
- -webkit-font-smoothing: antialiased for cleaner screen rendering
- Base font size: normal 16→17px, large 18→19px, small 14→15px
- Applies consistently to main UI, login, setup, settings, and help pages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/static/index.html

@@ -5,15 +5,18 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Cortex — Inara</title>
     <link rel="icon" href="data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 100 100'><text y='.9em' font-size='90'>✨</text></svg>">
+    <link rel="preconnect" href="https://fonts.googleapis.com">
+    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
+    <link href="https://fonts.googleapis.com/css2?family=Inter:wght@100..900&display=swap" rel="stylesheet">
     <!-- Apply saved theme + font size before first paint to avoid flash -->
     <script>
         (function(){
             var t = localStorage.getItem('theme');
             if (!t) t = window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light';
             document.documentElement.setAttribute('data-theme', t);
-            var sizes = { normal: '16px', large: '18px', small: '14px' };
+            var sizes = { normal: '17px', large: '19px', small: '15px' };
             var fs = localStorage.getItem('font-size') || 'normal';
-            document.documentElement.style.fontSize = sizes[fs] || '16px';
+            document.documentElement.style.fontSize = sizes[fs] || '17px';
         })();
     </script>
     <link rel="stylesheet" href="/static/style.css">