fix: eliminate 2s LCP rendering delay from Directus timeout on Hero

The Hero server component awaited getMessages(locale) which called Directus
with a 2-second timeout. On testing.dk0.dev (or when Directus is unreachable),
this blocked the entire Hero render for ~2s → LCP 3.0s / 2320ms rendering delay.

Changes:
- Hero.tsx: remove getMessages() call entirely; use t() for all strings
- messages/en.json + de.json: add hero.badge, hero.line1, hero.line2 keys
- lib/i18n-loader.ts: invert lookup order — JSON first, Directus only as
  override for keys absent from JSON. Previously Directus was tried first
  for every key, causing ~49 parallel network requests per page load in
  HomePageServer (aboutT + projectsT + contactT + footerT translations).
  Now all JSON-backed keys return instantly without any network I/O.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

messages/de.json

@@ -26,6 +26,9 @@
   },
   "home": {
     "hero": {
+      "badge": "Student & Self-Hoster",
+      "line1": "Building",
+      "line2": "Stuff.",
       "features": {
         "f1": "Next.js & Flutter",
         "f2": "Docker Swarm & CI/CD",