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/appinfo/info.xml

@@ -24,6 +24,12 @@
     <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>
+  </navigation>
   <repair-steps>
   <step>Repair steps not needed</step>
   <repair-step>Or remove and reinstall</repair-step>