alarms: compose subtag reference from object's real Galaxy area for exact alarmmgr parity

docs/AlarmClientDiscovery.md

@@ -818,6 +818,16 @@ subtags (confirmed AVEVA `AlarmExtension` field names, verified against the live
 ZB Galaxy `attribute_definition` rows). The gateway re-runs discovery on its
 reconcile cadence and pushes an updated watch-list when the model changes.
 
+Each target's canonical `AlarmFullReference` is composed as
+`Galaxy!{area}.{reference}` (literal `Galaxy` provider). The `{area}` is the
+alarm object's **real Galaxy area** — discovered per object via
+`gobject.area_gobject_id` (`GetAlarmAttributesAsync` projects it as `area_name`)
+— so the synthesized reference's group matches exactly the area the native
+alarmmgr (wnwrap) emits for the same alarm (e.g. `TestMachine_001` in `TestArea`
+yields `Galaxy!TestArea.TestMachine_001.TestAlarm001`). The configured
+`Discovery.Area` / `DefaultArea` is **only** the fallback for explicit
+`IncludeAttributes` entries, which carry no discovered area.
+
 ### Subtag advise and `LmxSubtagAlarmSource`
 
 `LmxSubtagAlarmSource` (implements `ISubtagAlarmSource`) owns a separate