fix: ensure slug and excerpt are never null to pass validation

- Extract slug generation to separate variable before using in DTO
- Convert null description to empty string for excerpt field
- Prevents class-validator from rejecting null values
- Fixes 'slug must be a string type' validation errors

backend/src/modules/strapi.service.ts

@@ -248,11 +248,15 @@ export class StrapiService {
           }
         }
 
+        // Generate slug if missing or null
+        const slug =
+          strapiArticle.slug || this.generateSlug(strapiArticle.title);
+
         const articleData: Partial<CreateArticleDto> = {
           title: strapiArticle.title,
-          excerpt: strapiArticle.description,
+          excerpt: strapiArticle.description || '',
           content: strapiArticle.content,
-          slug: strapiArticle.slug || this.generateSlug(strapiArticle.title),
+          slug,
           status: strapiArticle.publishedAt
             ? ArticleStatus.PUBLISHED
             : ArticleStatus.DRAFT,
@@ -335,11 +339,14 @@ export class StrapiService {
         }
       }
 
+      // Generate slug if missing or null
+      const slug = strapiArticle.slug || this.generateSlug(strapiArticle.title);
+
       const articleData: Partial<CreateArticleDto> = {
         title: strapiArticle.title,
-        excerpt: strapiArticle.description,
+        excerpt: strapiArticle.description || '',
         content: strapiArticle.content,
-        slug: strapiArticle.slug || this.generateSlug(strapiArticle.title),
+        slug,
         status,
         tags: [],
         featuredImage: imageUrl,