GET /v1/certificate-issuers
List the CAs a new certificate request may name
说明（契约原文）
lets_encrypt and each EAB CA (zerossl, google_trust) whose platform credentials are configured, with the platform default issuer. A request form offers only these; an unconfigured CA is not shown.
响应
| 状态码 | 说明 |
|---|---|
200 | Available issuers. 字段： |
401 | Authentication is required. |
403 | The active role lacks the required permission. |
失败时怎么办
401检查凭据格式、是否过期或被轮换。403检查 Key 范围与所有者当前权限、当前租户作用域；不要换更高权限账号绕过。