Fix: Change route from /admin to / to avoid Nextcloud conflicts

- Changed route URL from /admin to / (root path)
  - /admin was conflicting with Nextcloud built-in admin routes
  - Now uses apps/analyticshub/ instead
- Changed route name from admin#index to page#index
  - Follows Nextcloud naming conventions
- Updated info.xml navigation
  - Points to analyticshub.page.index
  - Removed <settings> section (can cause conflicts)
- Updated AdminController
  - Added request path to diagnostic output
  - Better styling for simple HTML page

The route was conflicting with Nextcloud's admin system.
New URL: https://teamworkapps.com/index.php/apps/analyticshub/

analyticshub/info.xml

@@ -10,11 +10,9 @@
   <category>integration</category>
   <dependencies>
     <nextcloud min-version="25" max-version="26"/>
+    <php min-version="7.4"/>
   </dependencies>
-  <settings>
-    <admin>OCA\AnalyticsHub\Controller\Admin</admin>
-  </settings>
   <navigation>
-    <admin>analyticshub.admin.index</admin>
+    <admin>analyticshub.page.index</admin>
   </navigation>
 </info>