Project convention is one FormRequest per endpoint
(Api/Post/StorePostRequest, UpdatePostRequest, etc.) — the inline
$request->validate() in attachMedia was the only outlier in this
controller. Extracted to Api/Post/AttachMediaRequest with the same
rules:
'urls' => ['required', 'array', 'min:1', 'max:10'],
'urls.*' => ['url:http,https', 'active_url'],
Controller signature is now AttachMediaRequest $request — Laravel
binds + validates before the action runs, same pattern as store/update.
ac361349da