HELP-1: in-app German user guide (/hilfe, accordion, 9 sections)

HilfePage.tsx: accordion via <details>/<summary> (native, accessible, mobile-first);
9 sections in du-Form: Erste Schritte, Rennmaeuse, Becken, Wuerfe, Genetik,
Stammbaum, Abgabe-Ablauf, Statistik, Datensicherung. All UI labels imported from
de.ts (rename-safe); SCHECKE/Rex warnings verbatim from genetics.warnings.

de.ts: de.nav.help + de.hilfe (title, subtitle, 9 section keys)
AppShell.tsx: Hilfe (heart question mark) added to SECONDARY nav (Mehr-sheet on phone,
sidebar on desktop)
App.tsx: Route path=hilfe -> <HilfePage />
hilfe.css: accordion, hint boxes, warning colour; piggybacks on existing CSS vars

e2e/hilfe.spec.ts: 3 smoke tests x 2 viewports = 6 new tests
  -- Hilfe reachable via nav
  -- First accordion section expands on click
  -- SCHECKE warning visible in Genetik section

Full evidence: dotnet test 18/18, npm test 47/47, npm run build ok,
npm run e2e 54/54 (48 existing + 6 new hilfe tests).

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

gerbil-manager-web/src/App.tsx

@@ -18,6 +18,7 @@ import WurfFormPage from './pages/WurfFormPage'
 import NotFoundPage from './pages/NotFoundPage'
 import StammbaumPage from './pages/StammbaumPage'
 import StatistikPage from './pages/StatistikPage'
+import HilfePage from './pages/HilfePage'
 
 export default function App() {
   return (
@@ -54,6 +55,7 @@ export default function App() {
           <Route path="genetik" element={<GenetikPage />} />
           <Route path="abgabe" element={<AbgabePage />} />
           <Route path="statistik" element={<StatistikPage />} />
+          <Route path="hilfe" element={<HilfePage />} />
           <Route path="*" element={<NotFoundPage />} />
         </Route>
       </Routes>