fix: stamp server info on graceful subscription results (#1078)

* fix: stamp server info on graceful subscription results

* fix: expose subscription server info metadata

---------

Co-authored-by: mrcs64 <9069178+mrcs64@users.noreply.github.com>

crates/rmcp/tests/test_subscriptions.rs

@@ -51,6 +51,7 @@ impl ServerHandler for ToolsOnlyServer {
                 .enable_tool_list_changed()
                 .build(),
         )
+        .with_server_info(Implementation::new("tools-only-server", "1.0.0"))
     }
 
     fn accepted_subscription_filter(
@@ -440,6 +441,13 @@ async fn listen_exposes_acknowledged_filter_and_graceful_result() -> anyhow::Res
         result.meta.subscription_id().as_ref(),
         Some(subscription.id())
     );
+    assert_eq!(
+        result
+            .meta
+            .server_info()
+            .expect("graceful result should contain valid server info"),
+        Implementation::new("tools-only-server", "1.0.0")
+    );
 
     client.cancel().await?;
     Ok(())