Bulk-create webhooks (up to 20 per request)
post
/v1/me/webhooks{batch}Partial-success semantics: each item succeeds or fails independently. Response is always 200 unless the request body itself is invalid (empty / too many items). Per-item failures carry an `error.code` (`invalid_url` | `invalid_channels` | `internal`). Each successful item returns a freshly-generated `secret` (only time it is shown).