Get All Available Zip Codes

The list of items returned in the response following given criteria.

Capped result count with Elasticsearch-style {value, relation} shape.

When the exact count is known and within the cap, relation is "eq" and value is that exact count. When the count exceeds the cap, relation is "gte" and value is the cap the count was probed against, meaning "the actual count is at least value". The cap is COUNT_CAP for every wire-facing endpoint; internal guard paths probe against their own cap, so value carries whatever cap produced it.