feat: plakat redesign phase 1 (tokens, fonts, poster hero, header) (#74)

- New design tokens: signal red, ink and paper as RGB channels; ink and paper
  swap roles in dark mode so every component inverts cleanly
- Fonts via next/font: Bricolage Grotesque (with wdth/opsz axes), Geist,
  Geist Mono; drop Inter and Playfair
- Poster hero: kicker, giant DK0 wordmark that reacts to pointer distance
  (weight and width through a damped spring, desktop only, off for reduced
  motion), claim as h1, intro with thesis countdown, marquee strip
- Header in poster style: transparent over the red hero, paper strip with
  ink rule when scrolled or on subpages; drawer menu restyled
- Remove wavy SVG separators, CSS shader gradient, background blobs and
  unused providers that caused the pink/purple bands between sections
- Drop the global p/span/div color override so colors inherit properly
- New hero texts in de/en, tests and i18n key check updated

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/__tests__/components/Hero.test.tsx

@@ -3,58 +3,38 @@ import Hero from '@/app/components/Hero';
 
 // Mock next-intl/server
 jest.mock('next-intl/server', () => ({
-  getTranslations: () => Promise.resolve((key: string) => {
-    const messages: Record<string, string> = {
-      badge: 'Student & Self-Hoster',
-      line1: 'Building',
-      line2: 'Stuff.',
-      description: 'Dennis is a student and passionate self-hoster.',
-      ctaWork: 'View My Work',
-      ctaContact: 'Get in touch',
-    };
-    return messages[key] || key;
-  }),
-}));
-
-// Mock next/image
-interface ImageProps {
-  src: string;
-  alt: string;
-  fill?: boolean;
-  priority?: boolean;
-  [key: string]: unknown;
-}
-
-jest.mock('next/image', () => ({
-  __esModule: true,
-  default: ({ src, alt, fill, priority, ...props }: ImageProps) => (
-    // eslint-disable-next-line @next/next/no-img-element
-    <img 
-      src={src} 
-      alt={alt} 
-      data-fill={fill?.toString()} 
-      data-priority={priority?.toString()} 
-      {...props} 
-    />
-  ),
+  getTranslations: () =>
+    Promise.resolve((key: string, values?: { days?: number }) => {
+      const messages: Record<string, string> = {
+        kicker: 'Dennis Konkol — Osnabrück, Germany',
+        claim: 'I self-host half my life. The rest I code.',
+        intro: "IT admin in Osnabrück and master's student.",
+        countdown: `${values?.days ?? 0} days to go.`,
+        ctaWork: 'See projects',
+        ctaContact: 'Write me',
+      };
+      return messages[key] || key;
+    }),
 }));
 
 describe('Hero', () => {
-  it('renders the hero section correctly', async () => {
+  it('renders the poster hero with claim, intro and calls to action', async () => {
     const HeroResolved = await Hero({ locale: 'en' });
     render(HeroResolved);
-    
-    // Check for the main headlines (defaults in Hero.tsx)
-    expect(screen.getByText('Building')).toBeInTheDocument();
-    expect(screen.getByText('Stuff.')).toBeInTheDocument();
-    
-    // Check for the description from our mock
-    expect(screen.getByText(/Dennis is a student/i)).toBeInTheDocument();
-    
-    // Check for the image
-    expect(screen.getByAltText('Dennis Konkol')).toBeInTheDocument();
-    
-    // Check for CTA
-    expect(screen.getByText('View My Work')).toBeInTheDocument();
+
+    expect(screen.getByRole('heading', { level: 1 })).toHaveTextContent('I self-host half my life. The rest I code.');
+    expect(screen.getByText('Dennis Konkol — Osnabrück, Germany')).toBeInTheDocument();
+    expect(screen.getByText(/IT admin in Osnabrück/)).toBeInTheDocument();
+    expect(screen.getByRole('link', { name: /See projects/ })).toHaveAttribute('href', '#projects');
+    expect(screen.getByRole('link', { name: 'Write me' })).toHaveAttribute('href', '#contact');
+  });
+
+  it('renders the DK0 wordmark as decoration hidden from assistive tech', async () => {
+    const HeroResolved = await Hero({ locale: 'en' });
+    const { container } = render(HeroResolved);
+
+    const wordmark = container.querySelector('[aria-hidden="true"].font-display');
+    expect(wordmark).not.toBeNull();
+    expect(wordmark).toHaveTextContent('DK0');
   });
 });