feat: plakat redesign phase 4 (chat window, contact, footer, cleanup) (#77)

- AI chat moves into a window/sheet, opened from a new speech-bubble card on
  the desk; it now respects the chatbot consent and asks before sending
  anything to n8n (previously it ignored the consent)
- Contact as red poster section with big mail address and the form on a paper
  card; validation errors are finally shown inline (aria-invalid, role=alert)
- Footer as ink strip with dk0 wordmark, legal links and a button to reopen
  the privacy settings
- "About me" in the header opens the about window on the home page
- Remove the old About section and its parts (BentoChat, ActivityFeed,
  CurrentlyReading, ReadBooks), the unused ChatWidget, Projects and BentoGrid,
  their tests, wrappers, loaders, types and texts
- scripts/directus-cleanup-redesign.mjs: dry run by default, --apply archives
  hobbies, tech stack categories and old content pages and deletes four
  unused message overrides after a full JSON backup; run only after the
  redesign is live on production

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

app/components/Header.tsx

@@ -17,7 +17,7 @@ const Header = () => {
 
   const navItems = [
     { name: t("home"), href: `/${locale}` },
-    { name: t("about"), href: isHome ? "#about" : `/${locale}#about` },
+    { name: t("about"), href: isHome ? "#projects" : `/${locale}#projects` },
     { name: t("projects"), href: isHome ? "#projects" : `/${locale}/projects` },
     { name: t("contact"), href: isHome ? "#contact" : `/${locale}#contact` },
   ];