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>

components/BackgroundBlobs.tsx

@@ -1,48 +0,0 @@
-"use client";
-
-import { motion } from "framer-motion";
-import { useEffect, useState } from "react";
-
-const BackgroundBlobs = () => {
-  const [mounted, setMounted] = useState(false);
-
-  useEffect(() => {
-    setMounted(true);
-  }, []);
-
-  if (!mounted) return null;
-
-  return (
-    <div className="fixed inset-0 overflow-hidden pointer-events-none z-0">
-      {/* Mint blob - top left */}
-      <motion.div
-        className="absolute top-[-10%] left-[-10%] w-[40vw] h-[40vw] bg-liquid-mint/40 rounded-full blur-[60px] opacity-70"
-        animate={{ scale: [1, 1.15, 1] }}
-        transition={{ duration: 40, repeat: Infinity, ease: "easeInOut", repeatType: "reverse" }}
-      />
-
-      {/* Lavender blob - top right */}
-      <motion.div
-        className="absolute top-[10%] right-[-5%] w-[35vw] h-[35vw] bg-liquid-lavender/35 rounded-full blur-[60px] opacity-70"
-        animate={{ scale: [1, 1.1, 1] }}
-        transition={{ duration: 45, repeat: Infinity, ease: "easeInOut", repeatType: "reverse" }}
-      />
-
-      {/* Rose blob - bottom left */}
-      <motion.div
-        className="absolute bottom-[-5%] left-[15%] w-[45vw] h-[45vw] bg-liquid-rose/35 rounded-full blur-[60px] opacity-70"
-        animate={{ scale: [1, 1.2, 1] }}
-        transition={{ duration: 50, repeat: Infinity, ease: "easeInOut", repeatType: "reverse" }}
-      />
-
-      {/* Peach blob - middle right */}
-      <motion.div
-        className="absolute top-[40%] right-[10%] w-[30vw] h-[30vw] bg-orange-200/30 rounded-full blur-[60px] opacity-70"
-        animate={{ scale: [1, 1.25, 1] }}
-        transition={{ duration: 55, repeat: Infinity, ease: "easeInOut", repeatType: "reverse" }}
-      />
-    </div>
-  );
-};
-
-export default BackgroundBlobs;