feat: hide logout button when admin is not logged in

- Add conditional rendering for "Abmelden" button based on isAdminLoggedIn state
- Button only appears when localStorage contains "isAdminLoggedIn": "true"
- Improves UI cleanliness by hiding unnecessary logout option for regular users
- Maintains existing admin warning banner and logout functionality when needed

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "cpl-v4",
-  "version": "1.6.669",
+  "version": "1.6.670",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "cpl-v4",
-      "version": "1.6.669",
+      "version": "1.6.670",
       "dependencies": {
         "@fontsource/roboto": "^5.1.0",
         "@headlessui/react": "^2.2.4",