x:Metric: say which node wrote each sample

Each node stores histograms as running totals since it started. A sample
didn't say which node wrote it (the node was only in the id's low bits),
so a reader couldn't diff totals per node, and the console diffed across
nodes: on the three-node production cluster the delivery attempt time
read 14.7 s over the last hour against 0.7 s from the nodes' own figures.

x:Metric/get now returns nodeId alongside timestamp, both from the id.
The telemetry suite checks every sample carries it.

tests/src/telemetry/metrics.rs

@@ -2,6 +2,8 @@
  * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <[email protected]>
  *
  * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
+ *
+ * Modified by Coffey Labs in 2026 for INBUXA.
  */
 
 use crate::utils::server::TestServer;
@@ -53,6 +55,15 @@ pub async fn test(test: &TestServer) {
     );
     assert_eq!(metrics.len(), metric_ids.len());
 
+    // Every sample says which node wrote it, so histogram totals can be
+    // diffed per node
+    for metric in metrics {
+        assert!(
+            metric.get("nodeId").is_some_and(|v| v.is_u64()),
+            "Missing nodeId in {metric}"
+        );
+    }
+
     // Fetch the last 48 hours of metrics
     let metric_ids = admin
         .registry_query(