@spec add_server(connection(), String.t(), map() | keyword(), keyword()) ::
  {:ok, map()} | {:error, term()}

Adds or replaces an MCP server entry under mcp_servers.<name>.

The attrs map should include either a stdio launcher (command) or a streamable HTTP URL (url).

@spec list_servers(
  connection(),
  keyword()
) :: {:ok, map()} | {:error, term()}

Lists configured MCP servers from the app-server config.

Options

• :include_layers - include layered config metadata (passed to config/read)
• :app_server - override the module used for config calls (defaults to Codex.AppServer)

@spec remove_server(connection(), String.t(), keyword()) ::
  {:ok, map()} | {:error, term()}

Removes a configured MCP server entry.