bug: mcpServers in agent doesn't support SSE server transport

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue
- [x] I have run `q doctor` in the affected terminal session
- [x] I have run `q restart` and replicated the issue again

### Operating system

macos

### Expected behaviour

I'd like to add mcp server with SSE for an agent, such as
```
"mcpServers": {
"my-first-mcp": {
"url": "http://localhost:8080/sse",
"timeout": 60000
}
}
```
But it complains that `command` is required. In the `agent-v1.json` file, [command is required](https://github.com/aws/amazon-q-developer-cli/blob/main/schemas/agent-v1.json#L87-L89).

### Actual behaviour

But it complains that `command` is required. In the `agent-v1.json` file, [command is required](https://github.com/aws/amazon-q-developer-cli/blob/main/schemas/agent-v1.json#L87-L89).

### Steps to reproduce

_No response_

### Environment

```yaml

```

Comienza leyendo schemas/agent-v1.json en la definición de comando enlazada y compárala con el manejo de la configuración del agente para mcpServers. Reproduce el error de validación con la configuración de URL mostrada y, después, sigue el soporte de transporte existente. El trabajo está terminado cuando un agente puede aceptar y usar un servidor MCP SSE sin requerir command.

Escrito por el modelo de indexación a partir del texto del issue.