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/src/vite-env.d.ts

@@ -1,2 +1,10 @@
 /// <reference types="vite/client" />
 /// <reference types="unplugin-vue-router/client" />
+
+interface ImportMetaEnv {
+	readonly VITE_DRUPAL_API_URL?: string;
+}
+
+interface ImportMeta {
+	readonly env: ImportMetaEnv;
+}