refac: DELETE /v1/user/{id}?expected_role_id=N, user.remove audit event, 409 target_role_not_found, GetAll returns its error, Own-scope visibility filter moved into repos, JSON tags removed from use-case types

api/pkg/apperr/messages.go

@@ -72,6 +72,7 @@ const InvalidLocaleErrorMessage = "invalid_locale"
 const SiteImageNotFoundErrorMessage = "image_not_found"
 const UseSetDefaultErrorMessage = "use_set_default"
 const InvalidReassignErrorMessage = "invalid_reassign"
+const ReassignTargetNotFoundErrorMessage = "target_role_not_found"
 const InvalidSocialTypeErrorMessage = "invalid_social_type"
 
 const AuthorNotFoundErrorMessage = "author_not_found"