fix: Fix navigation links and restore LanguageSwitcher

- Add missing nav keys to types.ts, de.ts, en.ts (sessions, buddies, stats, wishlist)
- Add LanguageSwitcher back to authenticated header
- Create /sessions page with SessionList
- Create /buddies page with BuddyList
- Create /stats page with StatsDashboard
- Create /wishlist placeholder page

src/components/HeroBanner.tsx

@@ -0,0 +1,85 @@
+'use client';
+
+import { useEffect, useState } from 'react';
+import { createClient } from '@/lib/supabase/client';
+import Link from 'next/link';
+import { ChevronRight } from 'lucide-react';
+
+interface Banner {
+    id: string;
+    title: string;
+    image_url: string;
+    link_target: string | null;
+    cta_text: string;
+}
+
+export default function HeroBanner() {
+    const [banner, setBanner] = useState<Banner | null>(null);
+    const [isLoading, setIsLoading] = useState(true);
+
+    useEffect(() => {
+        const fetchBanner = async () => {
+            try {
+                const supabase = createClient();
+                const { data, error } = await supabase
+                    .from('app_banners')
+                    .select('*')
+                    .eq('is_active', true)
+                    .limit(1)
+                    .maybeSingle();
+
+                if (!error && data) {
+                    setBanner(data);
+                }
+            } catch (err) {
+                console.warn('[HeroBanner] Failed to fetch:', err);
+            } finally {
+                setIsLoading(false);
+            }
+        };
+
+        fetchBanner();
+    }, []);
+
+    // Don't render if no active banner
+    if (isLoading || !banner) {
+        return null;
+    }
+
+    const content = (
+        <div
+            className="relative h-48 rounded-2xl overflow-hidden bg-zinc-900 group"
+            style={{
+                backgroundImage: `url(${banner.image_url})`,
+                backgroundSize: 'cover',
+                backgroundPosition: 'center',
+            }}
+        >
+            {/* Overlay gradient */}
+            <div className="absolute inset-0 bg-gradient-to-t from-black/80 via-black/20 to-transparent" />
+
+            {/* Content */}
+            <div className="absolute bottom-0 left-0 right-0 p-4">
+                <h3 className="text-lg font-bold text-white mb-1 line-clamp-2">
+                    {banner.title}
+                </h3>
+                {banner.link_target && (
+                    <div className="flex items-center gap-1 text-orange-500 text-xs font-bold uppercase tracking-wider">
+                        {banner.cta_text}
+                        <ChevronRight size={14} className="group-hover:translate-x-1 transition-transform" />
+                    </div>
+                )}
+            </div>
+        </div>
+    );
+
+    if (banner.link_target) {
+        return (
+            <Link href={banner.link_target} className="block">
+                {content}
+            </Link>
+        );
+    }
+
+    return content;
+}

src/components/NavButton.tsx

@@ -0,0 +1,32 @@
+'use client';
+
+import Link from 'next/link';
+import { ReactNode } from 'react';
+
+interface NavButtonProps {
+    icon: ReactNode;
+    label: string;
+    href: string;
+    badge?: number;
+}
+
+export default function NavButton({ icon, label, href, badge }: NavButtonProps) {
+    return (
+        <Link
+            href={href}
+            className="flex flex-col items-center justify-center gap-1.5 p-3 bg-zinc-900 hover:bg-zinc-800 border border-zinc-800 hover:border-zinc-700 rounded-xl transition-all active:scale-95"
+        >
+            <div className="relative text-zinc-400">
+                {icon}
+                {badge !== undefined && badge > 0 && (
+                    <span className="absolute -top-1 -right-1 w-4 h-4 bg-orange-600 rounded-full text-[8px] font-black text-white flex items-center justify-center">
+                        {badge > 9 ? '9+' : badge}
+                    </span>
+                )}
+            </div>
+            <span className="text-[10px] font-bold text-zinc-500 uppercase tracking-wide">
+                {label}
+            </span>
+        </Link>
+    );
+}

src/components/QuickActionsGrid.tsx

@@ -0,0 +1,34 @@
+'use client';
+
+import NavButton from './NavButton';
+import { Calendar, Users, BarChart3, Heart } from 'lucide-react';
+import { useI18n } from '@/i18n/I18nContext';
+
+export default function QuickActionsGrid() {
+    const { t } = useI18n();
+
+    return (
+        <div className="grid grid-cols-4 gap-3">
+            <NavButton
+                icon={<Calendar size={22} />}
+                label={t('nav.sessions') || 'Events'}
+                href="/sessions"
+            />
+            <NavButton
+                icon={<Users size={22} />}
+                label={t('nav.buddies') || 'Buddies'}
+                href="/buddies"
+            />
+            <NavButton
+                icon={<BarChart3 size={22} />}
+                label={t('nav.stats') || 'Stats'}
+                href="/stats"
+            />
+            <NavButton
+                icon={<Heart size={22} />}
+                label={t('nav.wishlist') || 'Wishlist'}
+                href="/wishlist"
+            />
+        </div>
+    );
+}