build: repair net40 Tray build and test-host binding redirects

Environment drift since ~7/26 broke a pristine checkout: (1) the SDK's
AutoGenerateBindingRedirects made RAR drop RioJoy.Core.dll for the net40
Tray exe (Bcl facade 1.5.11.0 vs 2.6.8.0 mismatch) - disabled for net40
with a hand-authored app.net40.config carrying the 2.6.8.0 redirects,
which XP's CLR 4.0 does not unify on its own; (2) 25 serial-link tests
failed on System.Runtime.CompilerServices.Unsafe load - Channels 8.0's
net462 binary references Unsafe 6.0.0.0 without declaring the dependency;
pinned the package and added the redirect app.config the earlier good
builds had auto-generated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/RioJoy.Tray/RioJoy.Tray.csproj

@@ -21,6 +21,16 @@
 
   <PropertyGroup Condition="'$(TargetFramework)' == 'net40'">
     <PlatformTarget>x86</PlatformTarget>
+    <!-- The SDK defaults AutoGenerateBindingRedirects=true for .NET Framework
+         exes, which makes RAR walk the dependency closure of the NuGet-resolved
+         Microsoft.Bcl.Async assemblies; those were compiled against Microsoft.Bcl
+         facades v1.5.11.0 while the graph ships v2.6.8.0, and RAR classifies the
+         missing 1.5.11.0 facades as unresolvable framework assemblies and drops
+         the references (MSB3268 → CS0234). Turning generation off skips that
+         walk; the redirects the XP runtime still needs are hand-authored in
+         app.net40.config instead. -->
+    <AutoGenerateBindingRedirects>false</AutoGenerateBindingRedirects>
+    <AppConfig>app.net40.config</AppConfig>
   </PropertyGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net40'">

src/RioJoy.Tray/app.net40.config

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- XP (net40) flavor only, selected via <AppConfig> in the csproj. The
+     Microsoft.Bcl.Async assemblies were compiled against the Microsoft.Bcl
+     facades v1.5.11.0, but the package graph ships v2.6.8.0; XP's CLR 4.0 has
+     no framework unification for these (4.5+ does), so without the redirects
+     the first TaskEx call throws FileLoadException. Build-time redirect
+     generation is off (see AutoGenerateBindingRedirects in the csproj), so the
+     redirects live here statically. The SDK adds the <startup> section. -->
+<configuration>
+  <runtime>
+    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+      <dependentAssembly>
+        <assemblyIdentity name="System.Runtime" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-2.6.8.0" newVersion="2.6.8.0" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.Threading.Tasks" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-2.6.8.0" newVersion="2.6.8.0" />
+      </dependentAssembly>
+      <dependentAssembly>
+        <assemblyIdentity name="System.IO" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-2.6.8.0" newVersion="2.6.8.0" />
+      </dependentAssembly>
+    </assemblyBinding>
+  </runtime>
+</configuration>

tests/RioJoy.Core.Tests/RioJoy.Core.Tests.csproj

@@ -15,6 +15,12 @@
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2" />
     <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
+    <!-- Channels 8.0's net462 binary references Unsafe 6.0.0.0 but doesn't
+         declare it, so the graph would otherwise resolve 4.5.3 (assembly
+         4.0.4.1) and the test host dies with FileLoadException. Pin the
+         assembly Channels was built against; app.config redirects the older
+         requests (System.Memory / Tasks.Extensions) up to it. -->
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="6.0.0" />
     <PackageReference Include="PolySharp" Version="1.14.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

tests/RioJoy.Core.Tests/app.config

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copied to RioJoy.Core.Tests.dll.config so the VSTest host binds the single
+     deployed System.Runtime.CompilerServices.Unsafe 6.0.0.0 (pinned in the
+     csproj — System.Threading.Channels 8.0's net462 binary requires it) for
+     the older versions System.Memory / System.Threading.Tasks.Extensions
+     request. Static rather than auto-generated so the suite doesn't depend on
+     RAR's redirect suggestions, which vary with the installed SDK/reference
+     assemblies. -->
+<configuration>
+  <runtime>
+    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+      <dependentAssembly>
+        <assemblyIdentity name="System.Runtime.CompilerServices.Unsafe" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
+        <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
+      </dependentAssembly>
+    </assemblyBinding>
+  </runtime>
+</configuration>