ST-1241: Verwijder frontend todo-UI (page, component, navbar en marketing page) (#133)

* feat(cleanup): verwijder Todo's navlink en todo-referenties uit marketing page [cmotto5ia000nx3178lq6xk8d]

- nav-bar.tsx: Todo's navLink verwijderd; Ideas-link blijft staan
- app/page.tsx: /todos quick-access link, feature-entry en /api/todos API-doc verwijderd

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

* feat(cleanup): verwijder app/(app)/todos/ en components/todos/ [cmottjvzo000cx3172472cu4g]

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

components/shared/nav-bar.tsx

@@ -143,7 +143,6 @@ export function NavBar({
             : disabledSpan('Solo')}
           {navLink('/insights', 'Insights', pathname.startsWith('/insights'))}
           {navLink('/ideas', 'Ideas', pathname.startsWith('/ideas'))}
-          {navLink('/todos', "Todo's", pathname.startsWith('/todos'))}
           {roles.includes('ADMIN') && navLink('/admin', 'Admin', pathname.startsWith('/admin'))}
         </nav>
       </div>