feat: add Drupal JSON:API service layer

- Create TypeScript interfaces for JSON:API responses (types/drupal.ts)
- Implement DrupalService class with getNodes(), getNode(), getTaxonomyTerms()
- Support pagination via getNextPage()
- Configure base URL via VITE_DRUPAL_API_URL environment variable
- Default uses CORS proxy at /api/drupal-proxy
- Add .env.example with configuration options

Phase1 tasks completed:
- Drupal instance with JSON:API verified working
- CORS proxy configured in nginx
- Content types created: article, page, learning_resource
- Taxonomies created: tags, categories

apps/vdn-static/.env.example

@@ -0,0 +1,6 @@
+# Drupal API Configuration
+# Use the CORS proxy for local development
+VITE_DRUPAL_API_URL=/api/drupal-proxy
+
+# For direct access (requires CORS on Drupal)
+# VITE_DRUPAL_API_URL=https://cms.viossa.net/jsonapi