refactor(historian): extract Driver.Historian.Sql.Common from the SQL Server backend (no behaviour change) (1a)

Moves the database-independent logic of the SQL Server historian backend into a new
shared library for the upcoming QuestDB backend (#666): status codes and bits, value/column
mapping, StoredSample + quality clamp, the AtTime and aggregate evaluators, BucketPlan,
LiveWritePreparer and HistoryUpdatePlanner (both with a resolutionTicks parameter, default 1),
tag-name rules, the bootstrap failure cache, health counters, alarm event ids, the event
continuation and severity clamp. The SQL Server backend now calls it; its T-SQL, TVP
builders, connection, bootstrapper and catalog stay.

Tests: StatusCodeOracleTests, ValueWriterPrepareTests, the column half of SampleRowMapperTests
and ProcessedReadTests.Every_enum_member_is_either_served_or_refused move to the new
Sql.Common.Tests under the same names. SqlServer integration tests get mechanical renames
only. Test-name set across the three projects is identical to the baseline (160 tests).

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions.Tests/ZB.MOM.WW.OtOpcUa.Core.Abstractions.Tests.csproj

@@ -43,6 +43,8 @@
              DriverTypeNames guard skips it — but it does hard-code OPC UA status constants, which
              puts it in StatusCodeParityTests' scope. -->
         <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway\ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway.csproj"/>
+        <!-- The SQL historian backends' shared status constants (HistorianStatusCodes) live here. -->
+        <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common\ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common.csproj"/>
         <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer\ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.csproj"/>
     </ItemGroup>