Generate Bearer Token
Generate a JWT Bearer Token using your API Key credentials.
**Authentication:** Pass your credentials via headers `x-key-id` and `x-secret-key`.
**Request body:** Optionally specify the `scopes` array to limit the token's permissions. If omitted, the token includes all scopes available to your API Key.
The returned token should be included in the `Authorization` header as `Bearer <token>` for all subsequent requests.

