Fix: Sidebar scrollable + add Eltern-Portal nav link

overflow-hidden → overflow-y-auto so all nav items are reachable.
Added /parent (Eltern-Portal) link with people icon.

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

studio-v2/components/Sidebar.tsx

@@ -71,6 +71,11 @@ export function Sidebar({ selectedTab = 'dashboard', onTabChange }: SidebarProps
         <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M9.663 17h4.673M12 3v1m6.364 1.636l-.707.707M21 12h-1M4 12H3m3.343-5.657l-.707-.707m2.828 9.9a5 5 0 117.072 0l-.548.547A3.374 3.374 0 0014 18.469V19a2 2 0 11-4 0v-.531c0-.895-.356-1.754-.988-2.386l-.548-.547z" />
       </svg>
     )},
+    { id: 'eltern', labelKey: 'nav_eltern', href: '/parent', icon: (
+      <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0zm6 3a2 2 0 11-4 0 2 2 0 014 0zM7 10a2 2 0 11-4 0 2 2 0 014 0z" />
+      </svg>
+    )},
     { id: 'vokabeln', labelKey: 'nav_vokabeln', href: '/vocab-worksheet', icon: (
       <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
         <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M7 21h10a2 2 0 002-2V9.414a1 1 0 00-.293-.707l-5.414-5.414A1 1 0 0012.586 3H7a2 2 0 00-2 2v14a2 2 0 002 2z" />
@@ -148,7 +153,7 @@ export function Sidebar({ selectedTab = 'dashboard', onTabChange }: SidebarProps
       onMouseEnter={() => setSidebarHovered(true)}
       onMouseLeave={() => setSidebarHovered(false)}
     >
-      <div className={`sticky top-4 h-[calc(100vh-32px)] backdrop-blur-2xl rounded-3xl border flex flex-col p-3 overflow-hidden ${
+      <div className={`sticky top-4 h-[calc(100vh-32px)] backdrop-blur-2xl rounded-3xl border flex flex-col p-3 overflow-y-auto overflow-x-hidden ${
         isDark
           ? 'bg-white/10 border-white/20'
           : 'bg-white/70 border-black/10 shadow-xl'