- 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.

resources/js/admin/i18n/locales/en/auth.json

@@ -0,0 +1,10 @@
+{
+  "login": {
+    "title": "Tenant Admin",
+    "lead": "Sign in with your Fotospiel account. We will redirect you to the secure OAuth login and bring you back to the admin dashboard afterwards.",
+    "cta": "Sign in with tenant account",
+    "loading": "Please wait …",
+    "oauth_error": "Sign-in failed: {{message}}",
+    "appearance_label": "Appearance"
+  }
+}