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.Contracts/Protos/mxaccess_gateway.proto

@@ -1003,9 +1003,13 @@ message StreamAlarmsRequest {
   string alarm_filter_prefix = 2;
 }
 
-// One message on the StreamAlarms feed. The stream opens with one
-// `active_alarm` per currently-active alarm, then a single
-// `snapshot_complete`, then a `transition` for every subsequent change.
+// One message on the StreamAlarms feed. The stream opens with a
+// `provider_status` (the current provider mode), then a `snapshot_status`
+// (whether the cached active set may be incomplete), then one `active_alarm`
+// per currently-active alarm, then a single `snapshot_complete`. After that
+// come the live frames: a `transition` for every subsequent alarm change,
+// interleaved with a further `provider_status` on each failover/failback and a
+// further `snapshot_status` on each change of the truncation verdict.
 message AlarmFeedMessage {
   oneof payload {
     // Part of the initial active-alarm snapshot (ConditionRefresh).