Lay the Almanacka design foundation: tokens, type, shell

New token system in global.css (near-white surfaces, one ink-blue
accent, no sub-12px type), self-hosted Schibsted Grotesk, rewritten
primitives (buttons, fields, modal shell, segmented, disclosure,
skeleton), a borderless 56px header with an SV | EN language toggle,
an Icon component replacing glyphs, page skeletons that keep the
layout during loading, and leave-type colours moved out of TS into
CSS variables. Feature blocks keep their structure for later phases.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

frontend/index.html

@@ -3,6 +3,13 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <link
+      rel="preload"
+      href="/fonts/SchibstedGrotesk-latin-v7.woff2"
+      as="font"
+      type="font/woff2"
+      crossorigin
+    />
     <title>Föräldraledigplannerare</title>
   </head>
   <body>