Fix: Add routes and admin navigation

- Created appinfo/routes.php to register all routes
  - Admin routes: index, save, load, getStatus
  - API v1 routes: reports, getReport, generate, getStatus
  - Report routes: index, generate
- Added index() method to AdminController
  - Renders admin template via TemplateResponse
- Updated info.xml and appinfo/info.xml
  - Fixed navigation entry to point to route: analyticshub.admin.index
  - Added settings and navigation sections
- App now appears in Settings → Administration after enable/disable

Fixes issue where app didn't show up in Nextcloud toolbar after being enabled.

analyticshub/info.xml

@@ -12,9 +12,9 @@
     <nextcloud min-version="25" max-version="26"/>
   </dependencies>
   <settings>
-    <admin>OCA\AnalyticsHub\Settings\Admin</admin>
+    <admin>OCA\AnalyticsHub\Controller\Admin</admin>
   </settings>
   <navigation>
-    <admin>OCA\AnalyticsHub\Settings\Admin</admin>
+    <admin>analyticshub.admin.index</admin>
   </navigation>
 </info>