docs(alarms): describe the real StreamAlarms open sequence, and close TST-16

The final integration review's non-blocker reservations, all documentation
or comment truth except one test arm.

The alarm feed opens provider_status -> snapshot_status -> cached
active_alarm -> snapshot_complete, which is what GatewayAlarmMonitor has
done since the snapshot_status frame landed. Two places still described
the old order: docs/Grpc.md said provider_status arrived *after* the
initial snapshot, contradicting its own snapshot_status section two
paragraphs down, and AlarmFeedMessage's leading proto comment named
neither status frame at all. Both now state the sequence the monitor
emits, so a client author reading either one gets the frame order right.

The proto comment change flows through the generated trees (Contracts,
Go, Java) and the client descriptor set; the Rust vendored copy stays
byte-identical to canonical. Python's generator does not carry proto
comments into its output, so it has no delta.

AlarmsHubPublisherTests' valueless-payload case covered snapshot_complete
and provider_status but not snapshot_status, leaving the newest arm
unpinned against the redaction switch that must ignore it. Added.

WnWrapAlarmConsumer's ack comment led with the 2026-05-01 reading that
-55 tracks the 8-arg overload, then refuted itself six lines later with
the 2026-08-18 probe. It now leads with the observation labelled as
narrower than it reads -- mirroring the correction already in
docs/AlarmClientDiscovery.md -- so the block argues one thing: the 6-arg
call site stays for parity, and rc semantics are per the probe. A
paragraph orphaned by an earlier splice is rewrapped. Comment interior
only; the file compiles on Windows.

TST-16 gets a dated closure note rather than a rewrite: the flag it
called dead was implemented 2026-08-18. GatewayDashboardDesign's /browse
paragraph gains the failed-read carve-out GatewayConfiguration already
documented, so the two agree that a failed read keeps its - placeholder.

src/ZB.MOM.WW.MxGateway.Tests/Gateway/Dashboard/AlarmsHubPublisherTests.cs

@@ -119,13 +119,21 @@ public sealed class AlarmsHubPublisherTests
             },
         };
 
+        AlarmFeedMessage snapshotStatus = new()
+        {
+            SnapshotStatus = new AlarmSnapshotStatus { Truncated = true },
+        };
+
         CapturingHubContext hubContext = await RunPublisherAsync(
             showTagValues: false,
             snapshotComplete,
-            providerStatus);
+            providerStatus,
+            snapshotStatus);
 
         Assert.Same(snapshotComplete, hubContext.Sent[0]);
         Assert.Same(providerStatus, hubContext.Sent[1]);
+        Assert.Same(snapshotStatus, hubContext.Sent[2]);
+        Assert.True(hubContext.Sent[2].SnapshotStatus.Truncated);
     }
 
     /// <summary>