List payers, sorted by ID ascending

Returns a page of payers from the shared payer catalog, ordered by id ascending — payer records carry no creation timestamp, so there is no "newest first" ordering. Use this to browse or discover payers before referencing one by ID (e.g. when associating a payer with a plan or network); use GET /payers/{id} once you already have a specific payer ID.

Requires the READ_PAYER permission. The tenant-id header is required, but the payer catalog is not tenant-partitioned: the value is forwarded downstream purely for audit-trail attribution and does not filter or restrict which payers are returned.

Pagination: always returns the first 10 records (offset 0); no caller-controlled pagination is currently exposed by this endpoint, even though the underlying payer service supports page/cursor-based pagination. This is a known limitation of this endpoint specifically, not fixed in this change.

Returns a GetAllPayersResponse with a data array of payer records and a totalCount. Each record's own data field is shaped per https://schemas.certifyos.com/entities/Payer.schema.json. This operation is read-only and has no side effects.