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>

lib/translations-loader.ts

@@ -2,7 +2,6 @@ import { getLocalizedMessage } from '@/lib/i18n-loader';
 import type {
   NavTranslations,
   FooterTranslations,
-  HeroTranslations,
   AboutTranslations,
   ProjectsTranslations,
   ContactTranslations,
@@ -55,30 +54,6 @@ export async function getFooterTranslations(locale: string): Promise<FooterTrans
   };
 }
 
-export async function getHeroTranslations(locale: string): Promise<HeroTranslations> {
-  const keys = [
-    'home.hero.description',
-    'home.hero.ctaWork',
-    'home.hero.ctaContact',
-    'home.hero.features.f1',
-    'home.hero.features.f2',
-    'home.hero.features.f3',
-  ];
-
-  const values = await Promise.all(keys.map(key => getLocalizedMessage(key, locale)));
-
-  return {
-    description: values[0],
-    ctaWork: values[1],
-    ctaContact: values[2],
-    features: {
-      f1: values[3],
-      f2: values[4],
-      f3: values[5],
-    },
-  };
-}
-
 export async function getAboutTranslations(locale: string): Promise<AboutTranslations> {
   const keys = [
     'home.about.title',