feat: add subscription listen streams (SEP-2575) (#1000)

* feat: add subscription listen streams

* refactor: reuse legacy request helper

examples/clients/src/subscriptions_streamhttp.rs

@@ -0,0 +1,49 @@
+use rmcp::{
+    ClientLifecycleMode, ClientServiceExt,
+    model::{ClientInfo, ProtocolVersion, SubscriptionFilter},
+    transport::StreamableHttpClientTransport,
+};
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| "info".into()),
+        )
+        .init();
+
+    let transport = StreamableHttpClientTransport::from_uri("http://127.0.0.1:8000/mcp");
+    let client = ClientInfo::default()
+        .serve_with_lifecycle(
+            transport,
+            ClientLifecycleMode::Discover {
+                preferred_versions: vec![ProtocolVersion::V_2026_07_28],
+            },
+        )
+        .await?;
+    let mut subscription = client
+        .listen(SubscriptionFilter::builder().tools_list_changed().build())
+        .await?;
+
+    println!("accepted filter: {:?}", subscription.acknowledged());
+    loop {
+        tokio::select! {
+            result = subscription.next() => {
+                match result? {
+                    Some(notification) => println!("notification: {notification:?}"),
+                    None => {
+                        println!("subscription ended: {:?}", subscription.end());
+                        break;
+                    }
+                }
+            }
+            _ = tokio::signal::ctrl_c() => {
+                subscription.cancel().await?;
+                break;
+            }
+        }
+    }
+
+    client.cancel().await?;
+    Ok(())
+}