Add new Client Dependency Injection project

A new project, `DigitalData.MessagingService.Client.DependencyInjection`, has been added to the solution.

- Updated `DigitalData.MessagingService.sln` to include the new project with its build configurations and nested project structure.
- Created `DigitalData.MessagingService.Client.DependencyInjection.csproj` targeting `net462`, `net480`, and `net8.0`.
- Added project metadata such as `PackageId`, `Authors`, `Version`, and more.
- Included a dependency on `RabbitMQ.Client` (v7.2.1).
- Configured nullable reference types and set the language version to `latest`.
- Added `icon.png` for NuGet packaging and enabled XML documentation generation.

src/presentation/DigitalData.MessagingService.Client.DependencyInjection/DigitalData.MessagingService.Client.DependencyInjection.csproj

@@ -0,0 +1,34 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFrameworks>net462;net480;net8.0</TargetFrameworks>
+		<DocumentationFile>bin\$(Configuration)\$(TargetFramework)\$(MSBuildProjectName).xml</DocumentationFile>
+		<PackageId>DigitalData.MessagingService.Client</PackageId>
+		<Authors>Digital Data GmbH</Authors>
+		<Company>Digital Data GmbH</Company>
+		<Product>DigitalData.MessagingService.Client</Product>
+		<Copyright>Copyright 2026</Copyright>
+		<PackageIcon>icon.png</PackageIcon>
+		<RepositoryUrl>http://git.dd:3000/AppStd/Rec.git</RepositoryUrl>
+		<PackageTags>digital data messaging service api client</PackageTags>
+		<Version>1.0.0-beta</Version>
+		<AssemblyVersion>1.0.0.0</AssemblyVersion>
+		<FileVersion>1.0.0.0</FileVersion>
+		<Description></Description>
+		<LangVersion>latest</LangVersion>
+		<Nullable>enable</Nullable>
+		<LangVersion>latest</LangVersion>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="RabbitMQ.Client" Version="7.2.1" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<None Include="..\..\..\assets\icon.png">
+			<Pack>True</Pack>
+			<PackagePath>\</PackagePath>
+		</None>
+	</ItemGroup>
+
+</Project>