Phase 4: Complete admin UI with TemplateResponse and configuration forms

- PageController: Replaced simple HTML with proper TemplateResponse
  - Added index() method with full admin interface
  - Added save() method for POST /save
  - Added load() method for GET /load
  - Injected IConfig service for configuration storage
  - Added validation for required fields
  - Proper error handling with JSONResponse

- Admin template: Full Nextcloud-compatible admin interface
  - Google Analytics configuration section (client ID, secret, refresh token)
  - Anthropic Claude API configuration section (API key)
  - Configuration status display (success/warning states)
  - Form with proper Nextcloud components
  - CSRF token handling

- Routes: Added /save and /load endpoints
  - page#index (GET) - renders admin page
  - page#save (POST) - saves configuration
  - page#load (GET) - loads configuration

- Application.php: Updated with APP_VERSION constant
  - Proper style and script loading

- CSS: Complete styling for admin interface
  - Responsive design with Nextcloud theme colors
  - Form input styling with focus states
  - Action buttons with hover effects

- JavaScript: Complete form handling
  - AJAX submission to /save endpoint
  - Configuration loading from /load endpoint
  - CSRF token handling with OC.requestToken
  - OC.Notification integration for success/error messages
  - Real-time status updates

This is a complete, working admin interface for configuration.
Users can now save/load Google Analytics and Claude API credentials through the UI.

analyticshub/appinfo/routes.php

@@ -10,12 +10,24 @@ namespace OCA\AnalyticsHub;
 
 return [
     'routes' => [
-        // Admin route - use root path
+        // Admin routes
         [
             'name' => 'page#index',
             'url' => '/',
             'verb' => 'GET',
             'requirements' => [],
         ],
+        [
+            'name' => 'page#save',
+            'url' => '/save',
+            'verb' => 'POST',
+            'requirements' => [],
+        ],
+        [
+            'name' => 'page#load',
+            'url' => '/load',
+            'verb' => 'GET',
+            'requirements' => [],
+        ],
     ],
 ];