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/rust/README.md

@@ -132,6 +132,15 @@ 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).
 
+`AlarmFeedStream` also carries that completeness verdict at feed level, as an
+`alarm_feed_message::Payload::SnapshotStatus` frame whose `truncated` field 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 `query_active_alarms`.
+
 The session helpers keep MXAccess handles visible:
 
 ```rust