fix(plugin): CloseIdleConnections silent no-op when tokenTransport wraps HTTP transport

tokenTransport now delegates CloseIdleConnections to the underlying
*http.Transport so http.Client.CloseIdleConnections() works through
the wrapper. Three plugin Close() methods updated to unwrap via
HTTPClientTransport before calling CloseIdleConnections.

RoundTrip now short-circuits when caller already set Authorization,
avoiding an unnecessary req.Clone allocation on the pass-through path.

config/parsing/router/parse.go

@@ -34,6 +34,7 @@ func ParseRouter(cfg *config.RouterConfig) router.Router {
 		case "http":
 			return router_plugin.NewHTTPPlugin(
 				cfg.Name, cfg.Plugin.Addr,
+				plugin.TokenOption(cfg.Plugin.Token),
 				plugin.TLSConfigOption(tlsCfg),
 				plugin.TimeoutOption(cfg.Plugin.Timeout),
 			)