Resolve blocking I/O finding and complete Historian lifecycle test coverage

Move subscribe/unsubscribe I/O outside lock(Lock) in SyncAddressSpace to avoid
blocking all OPC UA operations during rebuilds. Replace blocking ReadAsync calls
for alarm priority/description in dispatch loop with cached subscription values.
Extract IHistorianConnectionFactory so EnsureConnected can be tested without the
SDK runtime — adds 5 connection lifecycle tests (failure, timeout, reconnect,
state resilience, dispose-after-failure). All stability review findings and test
coverage gaps are now fully resolved.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.LmxOpcUa.Host/ZB.MOM.WW.LmxOpcUa.Host.csproj

@@ -53,6 +53,10 @@
             <HintPath>..\..\lib\aahClientManaged.dll</HintPath>
             <EmbedInteropTypes>false</EmbedInteropTypes>
         </Reference>
+        <Reference Include="aahClientCommon">
+            <HintPath>..\..\lib\aahClientCommon.dll</HintPath>
+            <EmbedInteropTypes>false</EmbedInteropTypes>
+        </Reference>
     </ItemGroup>
 
     <ItemGroup>