Searches enrollable-operator candidates for the Add-operator picker.

A DB-paged, name-searchable page of curated directory Persons who could be enrolled as an operator here, each carrying the server's verdict: `status` (`ELIGIBLE` / `PROMOTABLE` — enrolling first classifies them as internal — / `INELIGIBLE`) and, when ineligible, a stable `ineligibleReason` code. Existing operators, external customers, disabled people, groups and ambient identities are all filtered out — nothing an admin can act on — so in practice every row is selectable. Holding a served (customer) grant in this Application is <b>not</b> a rejection: per design §3 an internal teammate may be served and an operator at once. The `servedHere` flag says so for display only. This backs the picker's server-side type-ahead so it no longer loads the whole tenant directory or the whole served set. The verdict is the same predicate the enroll path enforces, so a selectable candidate is one `POST` accepts. The literal `candidates` segment out-ranks the `{operator}` route, so there is no collision.

curl -X GET "https://api.fruxon.com/v1/tenants/string/networks/497f6eca-6276-4993-bfeb-53cbbbba6f08/operators/candidates"

{
  "items": [
    {
      "participantId": "00000000-0000-0000-0000-000000000000",
      "displayName": "string",
      "kind": "PERSON",
      "audience": "UNKNOWN",
      "tier": "CURATED",
      "disabledAt": 0,
      "servedHere": false,
      "status": "ELIGIBLE",
      "ineligibleReason": "NOT_PERSON"
    }
  ],
  "nextPageToken": "string",
  "totalCount": 0
}

{
  "type": "string",
  "title": "string",
  "status": 0,
  "detail": "string",
  "instance": "string",
  "property1": null,
  "property2": null
}