feat: Ideas UI verbeteringen — hernoeming, tab-states, timeline refresh

- Nav-label 'Ideeën' hernoemd naar 'Ideas'; breadcrumb idem
- Grill/Plan tabs disabled (grijs, cursor-not-allowed) zolang er geen
  content is; groene stip zodra grill_md resp. plan_md beschikbaar is
- SSE hook roept router.refresh() aan bij job done/failed zodat de
  Timeline automatisch de nieuwe GRILL_RESULT/PLAN_RESULT logs toont

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

components/shared/nav-bar.tsx

@@ -140,7 +140,7 @@ export function NavBar({
               )
             : disabledSpan('Solo')}
           {navLink('/insights', 'Insights', pathname.startsWith('/insights'))}
-          {navLink('/ideas', 'Ideeën', pathname.startsWith('/ideas'))}
+          {navLink('/ideas', 'Ideas', pathname.startsWith('/ideas'))}
           {navLink('/todos', "Todo's", pathname.startsWith('/todos'))}
           {roles.includes('ADMIN') && navLink('/admin', 'Admin', pathname.startsWith('/admin'))}
         </nav>