loader in filter

use loader in filter form

The issue mentions using a loader in a filter form, but does not specify which component or file to modify. Look for filter-related components in the frontend codebase, likely in a forms or filters directory. Check for existing loader implementations to understand the pattern. Determine what 'done' looks like by seeing if the filter form shows a loading state during data fetching.

索引モデルが issue の本文から書いたものです。