fix: add missing slug and description fields to Article schema and fix auth header

backend/src/modules/strapi.service.ts

@@ -106,9 +106,13 @@ export class StrapiService {
   }
 
   private getHeaders() {
-    return {
-      Authorization: `Bearer ${this.strapiApiToken}`,
-    };
+    // Only include Authorization header if token is set
+    if (this.strapiApiToken) {
+      return {
+        Authorization: `Bearer ${this.strapiApiToken}`,
+      };
+    }
+    return {};
   }
 
   private async findOrCreateCategory(