chore: Limit the number of articles retrieved by widget (#11095)

The UI displays only six articles, and this update introduces a per_page
parameter to control the number of articles returned per API call. The
value is capped between 1 and 100, with a default fallback if a lower
number is set.

This change is necessary due to high website traffic, where excessive
payloads are returned without adding value.

**Changes:** 
- Add index to status, account_id, portal_id, views.
- Add per_page param in the API.
- Update the code in the frontend to fetch only 6

app/views/public/api/v1/portals/articles/index.json.jbuilder

@@ -4,5 +4,5 @@ json.payload do
 end
 
 json.meta do
-  json.articles_count @articles.published.size
+  json.articles_count @articles_count
 end