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/src/pages/Settings.test.tsx

@@ -199,7 +199,7 @@ describe('Settings', () => {
       })
     )
     renderSettings()
-    expect(screen.getByText(/Laddar inställningar/)).toBeInTheDocument()
+    expect(screen.getByTestId('page-skeleton')).toBeInTheDocument()
   })
 
   it('renders consistently Swedish section headings', () => {