- Reworked the tenant admin login page

- Updated the User model to implement Filament’s tenancy contracts
- Seeded a ready-to-use demo tenant (user, tenant, active package, purchase)
- Introduced a branded, translated 403 error page to replace the generic forbidden message for unauthorised admin hits
- Removed the public “Register” links from the marketing header
- hardened join event logic and improved error handling in the guest pwa.

docs/screenshots/tenant-admin-onboarding/01-welcome-hero.svg

@@ -0,0 +1,23 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1280 720">
+  <defs>
+    <linearGradient id="heroGradient" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" stop-color="#f43f5e"/>
+      <stop offset="50%" stop-color="#d946ef"/>
+      <stop offset="100%" stop-color="#6366f1"/>
+    </linearGradient>
+  </defs>
+  <rect width="1280" height="720" fill="url(#heroGradient)"/>
+  <text x="80" y="180" font-size="64" font-family="Inter, Arial, sans-serif" font-weight="700" fill="#ffffff">
+    Willkommen im Event-Erlebnisstudio
+  </text>
+  <text x="80" y="260" font-size="28" font-family="Inter, Arial, sans-serif" fill="#fdf2f8">
+    Führe Gäste durch Fotochallenges, Likes und Erinnerungen – alles in einer Admin-App.
+  </text>
+  <rect x="80" y="320" width="320" height="72" rx="36" fill="#111827" opacity="0.9"/>
+  <text x="120" y="368" font-size="28" font-family="Inter, Arial, sans-serif" fill="#ffffff">
+    Pakete entdecken
+  </text>
+  <text x="80" y="420" font-size="22" font-family="Inter, Arial, sans-serif" fill="#fef2f2">
+    oder Demo überspringen
+  </text>
+</svg>