feat: plakat redesign phase 2 (desk with throwable objects, mobile card deck) (#75)

- New "Tisch" section replaces the old projects block on the home page
- Objects: project cards from Directus (flip on tap, link to detail page),
  thesis ticket with countdown, server card, currently-reading book from
  Hardcover (with skeleton), polaroid photo, sticker
- Desktop: Framer Motion drag with momentum, elastic table edges, tilt that
  follows throw velocity, bring-to-front, "Tidy up" and "Mess it up"
- Mobile: card deck, swipe the top card away (distance or velocity),
  prev/next buttons, live counter, tap to flip
- Both layouts are server rendered and switched by CSS, so content is
  visible without JavaScript and nothing jumps on hydration
- Taps after a drag no longer flip cards
- New named colors polaroid/bookcover instead of raw hex classes
- Texts in de/en, i18n key check extended

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

tailwind.config.ts

@@ -96,6 +96,9 @@ export default {
           2: "rgb(var(--plakat-paper-2) / <alpha-value>)",
         },
         ok: "rgb(var(--plakat-ok) / <alpha-value>)",
+        // 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",