feat: plakat redesign for subpages (projects, books, legal, privacy)

- Shared SubpageShell (HeaderClient paper strip + ink footer) and SubpageIntro,
  btn/ghost/card helpers in app/_ui/subpage.tsx
- Projects list: poster cards with hard ink shadows, filter pills, ink search field;
  no fake 800ms skeleton and no framer-motion opacity:0 in SSR
- Project detail: poster hero, .plakat-prose markdown, links/stack aside,
  back link works without JS
- Books: server-side fetch (visible without JS), cover + rating pills
- Legal notice / privacy: moved to app/_ui/*Client.tsx, root routes removed
  (middleware always redirects to /[locale]), consent reset via useConsent
- ProjectThumbnail rebuilt on Plakat tokens
- Old Header.tsx + test removed; brown/cream/sand palettes and unused
  glass-panel/admin-glass(-light)/liquid-bg-blob/float CSS dropped
  (liquid palette, glass-card, admin-glass-card stay for admin + 404)
- .plakat-prose replaces the missing typography plugin

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

tailwind.config.ts

@@ -99,21 +99,6 @@ export default {
         // Feste Objektfarben auf dem Tisch, unabhängig vom Theme
         polaroid: { DEFAULT: "#fbfaf8", ink: "#140c0b" },
         bookcover: { DEFAULT: "#2b1a14", text: "#f3e7dc" },
-        // Warm brown palette
-        cream: "#FAF8F3",
-        sand: "#EFEBE9",
-        brown: {
-          50: "#EFEBE9",
-          100: "#D7CCC8",
-          200: "#BCAAA4",
-          300: "#A1887F",
-          400: "#8D6E63",
-          500: "#795548",
-          600: "#6D4C41",
-          700: "#5D4037",
-          800: "#4E342E",
-          900: "#3E2723",
-        },
         stone: {
           50: "#FAFAF9",
           100: "#F5F5F4",
@@ -126,6 +111,7 @@ export default {
           800: "#292524",
           900: "#1C1917",
         },
+        // Alte Pastellpalette, nur noch im Admin-Bereich und auf der 404-Seite
         liquid: {
           mint: "#A7F3D0",
           lavender: "#DDD6FE",