Fix: Simplify integration and fix admin template

- Removed settings/navigation from appinfo/info.xml
  - These sections can cause routing conflicts
  - App now relies purely on routes.php
- Simplified Application.php
  - Removed manual service/controller registration
  - Let Nextcloud DI framework handle it automatically
- Fixed admin template to use Nextcloud standards
  - Removed non-standard style() call
  - Added proper l10n support with p($l->t(...))
  - Clean template structure
- Created css/admin.css
  - Nextcloud-compatible styling
  - Matches design language
- Created js/admin.js
  - Handles Save Configuration button
  - Handles Test Connection button
  - Uses OC, OC.Notification APIs

This should fix admin page not appearing issue.
Users can access via: Settings → Administration → Additional Settings

analyticshub/appinfo/Application.php

@@ -18,7 +18,7 @@ class Application extends App {
     public function __construct(array $urlParams = []) {
         parent::__construct(self::APP_ID, $urlParams);
 
-        // Load scripts and styles
+        // Load scripts and styles for admin page
         Util::addStyle(self::APP_ID, 'admin');
         Util::addScript(self::APP_ID, 'admin');
     }