feat(ee): Add article translation via LLM in help center (#14136)

Adds the ability to translate help center articles to other languages using Captain's LLM infrastructure. Translated articles are created as drafts linked to the source article.

Fixes
https://linear.app/chatwoot/issue/CW-6901/translate-article-to-another-language

**How to test**

1. Navigate to Help Center → Articles for a portal with multiple locales
2. Click the three-dot menu on any article → "Translate"
3. Select a target language and category → click Translate
4. Switch to the target locale — the translated article appears as a
draft
5. Try translating the same article again — a warning shows the existing
translation with a link to open it in a new tab
6. Click "Overwrite and translate" to replace the existing translation


https://github.com/user-attachments/assets/1d2e991b-f0ac-403a-bcc1-2181b5731ea4

app/javascript/dashboard/api/helpCenter/articles.js

@@ -72,6 +72,13 @@ class ArticlesAPI extends PortalsAPI {
       category_slug: categorySlug,
     });
   }
+
+  bulkTranslate({ portalSlug, articleIds, locale, categoryId, force = false }) {
+    return axios.post(
+      `${this.url}/${portalSlug}/articles/bulk_actions/translate`,
+      { ids: articleIds, locale, category_id: categoryId, force }
+    );
+  }
 }
 
 export default new ArticlesAPI();