Add test reproductions from PR #4155 and #4003

PR #4155: Integration tests for bucketed multi-database tenancy with
hash-based document partitioning across shard databases.

PR #4003: Test for single-tenanted documents in multi-tenancy
partitioned ancillary stores.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jeremydmiller

Directory.Packages.props

@@ -58,6 +58,7 @@
     <PackageVersion Include="Shouldly" Version="4.3.0" />
     <PackageVersion Include="StronglyTypedId" Version="1.0.0-beta08" />
     <PackageVersion Include="Swashbuckle.AspNetCore" Version="6.5.0" />
+    <PackageVersion Include="System.IO.Hashing" Version="10.0.3" />
     <PackageVersion Include="Vogen" Version="7.0.0" />
     <PackageVersion Include="Weasel.EntityFrameworkCore" Version="8.9.0" />
     <PackageVersion Include="Weasel.Postgresql" Version="8.9.0" />

src/MultiTenancyTests/MultiTenancyTests.csproj

@@ -30,6 +30,7 @@
 
         <PackageReference Include="NSubstitute" />
         <PackageReference Include="Shouldly" />
+        <PackageReference Include="System.IO.Hashing" />
     </ItemGroup>
 
     <ItemGroup>