Rust client: port stream-alarms and acknowledge-alarm + fix stream-events family + 8MB Windows stack

Adds the session-less alarm CLI subcommands to mxgw. stream-alarms attaches to
the gateway's central alarm feed (--filter-prefix, --max-events, --json/--jsonl;
aggregate shape `{messageCount, messages: [...]}`); acknowledge-alarm is a unary
ack (--reference required, --comment, --operator). stream_alarms joins
query_active_alarms on GatewayClient and re-exports AlarmFeedStream.

Also extends stream-events JSON to emit a full `events` array (itemHandle, value
projected to protojson-shaped `*Value` keys, etc.) instead of just `eventCount`,
matching the other four CLIs, and renders MxEvent.family as the protobuf enum
NAME (MX_EVENT_FAMILY_ON_WRITE_COMPLETE) rather than the raw i32 so the e2e
write round-trip can recognise the OnWriteComplete echo.

Adds clients/rust/.cargo/config.toml bumping the Windows main-thread stack to
8 MB via /STACK:8388608. clap-derive's Command enum (one variant per subcommand)
overflowed the default 1 MB stack in debug builds after the new variants
landed; release builds were unaffected but the e2e matrix runs Rust via
`cargo run` (debug).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/rust/tests/proto_fixtures.rs

@@ -1,12 +1,12 @@
 use std::fs;
 use std::path::PathBuf;
 
+use serde_json::Value;
 use zb_mom_ww_mxgateway_client::generated::mxaccess_gateway::v1::{
     mx_command, mx_value, MxCommand, MxCommandKind, MxCommandRequest, MxDataType, MxEvent,
     MxEventFamily, MxValue, OpenSessionReply, ProtocolStatusCode, RegisterCommand,
 };
 use zb_mom_ww_mxgateway_client::{GATEWAY_PROTOCOL_VERSION, WORKER_PROTOCOL_VERSION};
-use serde_json::Value;
 
 #[test]
 fn generated_golden_fixtures_are_available() {