Fix: Corrected Application.php and controller namespace structure

- appinfo/Application.php: Namespace OCA\AnalyticsHub\AppInfo, Class Application
- appinfo/info.xml: Namespace AnalyticsHub, Navigation analyticshub.page.index
- lib/Controller/PageController.php: Namespace OCA\AnalyticsHub\Controller\Page, Class PageController
- This follows standard Nextcloud autoloader conventions
- Application extends OCP\AppFramework\App
- PageController extends OCP\AppFramework\Controller

Should fix autoloader issues:
- AppInfo class in AppInfo namespace (correct)
- PageController class in Controller namespace (correct)
- Navigation points to page.index (correct)
- Application.php has correct extends App

This should resolve all Application class loading errors and allow admin page to load properly.

analyticshub/lib/Controller/Page.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\AnalyticsHub\Controller\Page;
+
+use OCP\IRequest;
+use OCP\AppFramework\Controller;
+use OCP\AppFramework\Http\TemplateResponse;
+
+/**
+ * Admin Page Controller
+ *
+ * @NoAdminRequired
+ * @NoCSRFRequired
+ */
+class PageController extends Controller {
+
+    protected $appName;
+
+    public function __construct(string $appName, IRequest $request) {
+        parent::__construct($appName, $request);
+        $this->appName = $appName;
+    }
+
+    /**
+     * Index page - render admin UI
+     *
+     * @NoAdminRequired
+     * @NoCSRFRequired
+     */
+    public function index(): TemplateResponse {
+        return new TemplateResponse($this->appName, 'admin', [
+            'app_name' => $this->appName,
+            'version' => '1.0.0',
+            'status' => 'Testing - admin accessible',
+        ]);
+    }
+}