chore(clients): roll out feed-level snapshot_status to all five clients

Task 1 added AlarmSnapshotStatus and AlarmFeedMessage.snapshot_status = 5.
Carry it downstream from the canonical Contracts protos:

- Rust vendored protos under clients/rust/protos, refreshed byte-identical
  (build.rs falls back to them for out-of-repo tarball builds)
- client descriptor set (protoc 34.1 pin)
- Go (protoc-gen-go v1.36.11 / protoc-gen-go-grpc 1.6.2)
- Python (grpcio-tools 1.80.0 pin)
- Java (gradle generateProto)

.NET needs no regeneration: the client compiles against the Contracts
Generated/ output committed with the proto change.

The hand-written CLI feed renderers switch on the payload oneof, so codegen
alone does not carry the arm. Add snapshot-status to the .NET, Go, Rust, and
Java renderers; the .NET and Go renderers were also missing provider-status,
which has been on the wire since the provider-mode work, so add it there too.
Java's renderer is an exhaustive switch expression and did not compile until
the new case landed. The Python CLI renders generic protobuf-JSON and needs
no change.

Each client README gains a paragraph on the feed-level frame next to its
existing from_truncated_snapshot paragraph: it arrives at stream open after
provider_status and before the cached active_alarm frames, then on every
verdict change including the clearing frame a monitor restart emits, so a
live consumer can track set completeness without polling QueryActiveAlarms.

GatewayDashboardDesign: list the two new payload cases the AlarmsHub forwards,
and — separately — record the GroupToRole / GroupToTag / UntaggedSessionVisibility
rows the settings page already renders but the bullet list omitted.

clients/dotnet/README.md

@@ -156,6 +156,16 @@ poll. Treat the set as possibly incomplete rather than reconciling deletions
 from it. It is set-level degraded status, not a comment on the record's own
 fidelity, and is distinct from `Degraded` (the subtag fallback provider).
 
+`StreamAlarmsAsync` also carries that completeness verdict at feed level, as an
+`AlarmFeedMessage.PayloadOneofCase.SnapshotStatus` frame whose
+`SnapshotStatus.Truncated` is true while the monitor's cached set derives from a
+truncated fetch. One arrives at stream open (after the `ProviderStatus` frame,
+before the cached `ActiveAlarm` frames) so a late joiner learns the current
+verdict, then one on every verdict change — including the clearing frame sent
+when the gateway's alarm monitor restarts and drops a truncated verdict. Track
+it if you need set completeness on a live feed without polling
+`QueryActiveAlarmsAsync`.
+
 `MxGatewaySession.CloseAsync` is explicit and idempotent. Repeated calls return
 the first `CloseSessionReply` instead of sending another close request.