feat: add local feature for !Send tool handler support (#740)

* feat: add local feature for !Send tool handler support

* fix: gate streamable HTTP transport on not(local) feature

crates/rmcp/src/service/client.rs

@@ -162,7 +162,8 @@ impl<S: Service<RoleClient>> ServiceExt<RoleClient> for S {
         self,
         transport: T,
         ct: CancellationToken,
-    ) -> impl Future<Output = Result<RunningService<RoleClient, Self>, ClientInitializeError>> + Send
+    ) -> impl Future<Output = Result<RunningService<RoleClient, Self>, ClientInitializeError>>
+    + MaybeSendFuture
     where
         T: IntoTransport<RoleClient, E, A>,
         E: std::error::Error + Send + Sync + 'static,