A.3 (alarm-ack-by-name): public AcknowledgeAlarm now accepts Provider!Group.Tag references

Closes the gap where the public AcknowledgeAlarm RPC required canonical
GUIDs but OnAlarmTransitionEvent.AlarmFullReference is "Provider!Group.Tag".
Adds an AVEVA AlarmAckByName path that wraps wwAlarmConsumerClass.AlarmAckByName
so callers can ack with the natural reference.

Proto:
- New MxCommandKind.AcknowledgeAlarmByName (=29).
- New AcknowledgeAlarmByNameCommand(alarm_name, provider_name, group_name,
  comment, operator_user/node/domain/full_name) on MxCommand oneof.
- AcknowledgeAlarmReplyPayload (existing) carries the AVEVA native
  status; reused for the by-name path.

Worker:
- IMxAccessAlarmConsumer + WnWrapAlarmConsumer + AlarmDispatcher +
  AlarmCommandHandler all gain an AcknowledgeByName(name, provider,
  group, comment, operator-identity) overload that maps to
  wwAlarmConsumerClass.AlarmAckByName.
- MxAccessCommandExecutor: new switch arm routes
  MxCommandKind.AcknowledgeAlarmByName to the handler. Empty alarm_name
  yields InvalidRequest; handler exceptions surface as MxaccessFailure.

Gateway:
- WorkerAlarmRpcDispatcher.TryParseAlarmReference: parses
  "Provider!Group.Tag" with the convention that the FIRST '!' separates
  provider, the FIRST '.' after '!' separates group; tag may contain
  more dots.
- AcknowledgeAsync now branches: GUID input → AcknowledgeAlarm command
  (existing path); reference input → AcknowledgeAlarmByName command
  (new path); neither parses → InvalidRequest with a clear diagnostic.

Tests: 13 new unit tests cover each layer end-to-end:
- WorkerAlarmRpcDispatcher.TryParseAlarmReference (3 valid + 8 invalid
  forms) including the realistic 4-component "Galaxy!TestArea.
  TestMachine_001.TestAlarm001" reference.
- WorkerAlarmRpcDispatcher.AcknowledgeAsync routes references through
  AcknowledgeAlarmByName + propagates the full operator tuple.
- Executor switch arm carries the by-name tuple and rejects empty
  alarm_name.
- AlarmDispatcher.AcknowledgeByName forwards to consumer.
- Existing fakes extended for the new overload.

Counts: server 308/0, worker 195/3 skip / 1 pre-existing structure-fail
(untouched). Solution builds clean.

End-to-end alarms-over-gateway now serves the full lmxopcua flow:
client.AcknowledgeAlarm(reference="Galaxy!TestArea.TestMachine_001.TestAlarm001",
operator_user="alice") → gateway parses → IPC AcknowledgeAlarmByName →
worker AlarmAckByName → AVEVA history. The remaining piece for full
parity is a live dev-rig smoke test.

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

src/MxGateway.Contracts/Protos/mxaccess_gateway.proto

@@ -92,6 +92,7 @@ message MxCommand {
     UnsubscribeAlarmsCommand unsubscribe_alarms = 35;
     AcknowledgeAlarmCommand acknowledge_alarm_command = 36;
     QueryActiveAlarmsCommand query_active_alarms_command = 37;
+    AcknowledgeAlarmByNameCommand acknowledge_alarm_by_name_command = 38;
     PingCommand ping = 100;
     GetSessionStateCommand get_session_state = 101;
     GetWorkerInfoCommand get_worker_info = 102;
@@ -130,6 +131,7 @@ enum MxCommandKind {
   MX_COMMAND_KIND_UNSUBSCRIBE_ALARMS = 26;
   MX_COMMAND_KIND_ACKNOWLEDGE_ALARM = 27;
   MX_COMMAND_KIND_QUERY_ACTIVE_ALARMS = 28;
+  MX_COMMAND_KIND_ACKNOWLEDGE_ALARM_BY_NAME = 29;
   MX_COMMAND_KIND_PING = 100;
   MX_COMMAND_KIND_GET_SESSION_STATE = 101;
   MX_COMMAND_KIND_GET_WORKER_INFO = 102;
@@ -307,6 +309,27 @@ message QueryActiveAlarmsCommand {
   string alarm_filter_prefix = 1;
 }
 
+// Acknowledge a single alarm by its (name, provider, group) tuple. Used
+// when the public RPC's AlarmFullReference (Provider!Group.Tag) cannot
+// be resolved to a GUID directly. The worker invokes
+// wwAlarmConsumerClass.AlarmAckByName which reaches the same alarm
+// history path as AlarmAckByGUID.
+message AcknowledgeAlarmByNameCommand {
+  // Tag/alarm name (e.g. "TestMachine_001.TestAlarm001"). Tag itself
+  // may contain dots; the gateway-side parser splits on the first dot
+  // after the '!' separator.
+  string alarm_name = 1;
+  // AVEVA alarm-provider name (literal "Galaxy" for ArchestrA Galaxies).
+  string provider_name = 2;
+  // Area/group name (e.g. "TestArea").
+  string group_name = 3;
+  string comment = 4;
+  string operator_user = 5;
+  string operator_node = 6;
+  string operator_domain = 7;
+  string operator_full_name = 8;
+}
+
 message UnsubscribeBulkCommand {
   int32 server_handle = 1;
   repeated int32 item_handles = 2;