sidecar: switch Wonderware historian sidecar from x86 to x64

The sidecar was set to PlatformTarget=x86 + Prefer32Bit=true to mirror
v1's Driver.Galaxy.Host bitness, which itself was x86 only because of
MXAccess COM. PR 7.2 retired Galaxy.Host, so that constraint is gone.

AVEVA Historian 2020 ships an x64 build of every SDK assembly the
sidecar needs (lib\aahClientManaged.dll + aahClient.dll + aahClientCommon.dll
sourced from C:\Program Files (x86)\Wonderware\Historian\x64\; the
remaining three SDK assemblies — Historian.CBE / DPAPI /
ArchestrA.CloudHistorian.Contract — are pure-managed AnyCPU and load
in either bitness). Drop PlatformTarget to x64 on both the sidecar
project and its test project; running 37/37 historian tests + the
live install confirms the SDK loads and serves the named pipe in a
64-bit-native process.

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

src/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.csproj

@@ -3,10 +3,13 @@
     <PropertyGroup>
         <OutputType>Exe</OutputType>
         <TargetFramework>net48</TargetFramework>
-        <!-- x86 to match the in-process bitness expectations of the Wonderware Historian SDK
-             that PR 3.2 lifted in. Mirrors Driver.Galaxy.Host's bitness for consistency. -->
-        <PlatformTarget>x86</PlatformTarget>
-        <Prefer32Bit>true</Prefer32Bit>
+        <!-- x64 — AVEVA Historian 2020 ships an x64 build of aahClientManaged + the native
+             aahClient.dll under the Historian install's x64\ subfolder. The other three
+             SDK assemblies (Historian.CBE / DPAPI / ArchestrA.CloudHistorian.Contract) are
+             pure-managed AnyCPU and load fine in either bitness. The earlier x86 default
+             was inherited from v1's Galaxy.Host bitness (MXAccess COM, retired in PR 7.2)
+             and didn't reflect any constraint of the Historian SDK itself. -->
+        <PlatformTarget>x64</PlatformTarget>
         <Nullable>enable</Nullable>
         <LangVersion>latest</LangVersion>
         <TreatWarningsAsErrors>true</TreatWarningsAsErrors>

tests/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Tests/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Tests.csproj

@@ -2,8 +2,7 @@
 
     <PropertyGroup>
         <TargetFramework>net48</TargetFramework>
-        <PlatformTarget>x86</PlatformTarget>
-        <Prefer32Bit>true</Prefer32Bit>
+        <PlatformTarget>x64</PlatformTarget>
         <Nullable>enable</Nullable>
         <LangVersion>latest</LangVersion>
         <IsPackable>false</IsPackable>