通过 OpenRouter 连接模型服务

用户 config 写 [model_providers.openrouter]，base_url 是 https://openrouter.ai/api/v1，wire_api = responses。主路径是 [model_providers.openrouter.auth] 用 sh 回显 OPENROUTER_API_KEY，与 env_key 二选一。

[model_providers.openrouter]
name = "openrouter"
base_url = "https://openrouter.ai/api/v1"
wire_api = "responses"

[model_providers.openrouter.auth]
command = "sh"
args = ["-c", "echo $OPENROUTER_API_KEY"]