fix: usable on phones — menu, no sideways scrolling, whole roadmap intro

- The navigation had no mobile layout: every page was 413px wider than a
  phone. Below lg the links now sit behind a menu button, grouped like the
  desktop dropdowns; the menu closes on navigation.
- Glossary tooltips were invisible but still laid out, so a term near the
  right edge widened the page. Hidden tooltips no longer take up space;
  they show on hover and on keyboard focus as before.
- Long German words in page headings ("produktionstauglich",
  "Konfigurationstiefe") overflowed at 360px; headings start a size smaller
  on phones.
- The roadmap intro dropped everything after its second "NIS2" ("…the
  baseline requirements of"); it is split at the first one only now.

Checked at 360, 390 and 768px on every page: no horizontal overflow.

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

src/pages/ForItSupport.tsx

@@ -62,7 +62,7 @@ export default function ForItSupport() {
           <div className="mb-4 flex h-10 w-10 items-center justify-center rounded-lg bg-sky-600/10">
             <LifebuoyIcon className="h-5 w-5 text-sky-400" />
           </div>
-          <h1 className="text-4xl md:text-5xl font-bold text-slate-100 mb-4">{t.forItSupport.heading}</h1>
+          <h1 className="text-3xl sm:text-4xl md:text-5xl font-bold text-slate-100 mb-4">{t.forItSupport.heading}</h1>
           <p className="text-base text-slate-400 leading-relaxed max-w-2xl">{linkify(t.forItSupport.sub)}</p>
         </div>