Remove target-conditional properties

[breyed]

Previously, the project file had properties that were conditional based on the build target. This caused me to infer that the project was meant to be built multiple times with different targets set as a workaround for proper multi-targeting.

This PR removes the conditions (which weren't needed anyway) and adds a comment clarifying that a single target is intended for use across all frameworks.

[Copilot]

Pull Request Overview

This PR removes target-conditional properties from the .NET project file that were unnecessarily complicating the build configuration. The PR clarifies that the project is intended to use a single target framework (net472) that works across all supported .NET versions.

• Removes conditional PropertyGroup elements that defined preprocessor constants based on target framework
• Removes condition from ItemGroup that referenced .NET Framework assemblies
• Adds explanatory comment about framework compatibility strategy

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[Copilot]

Removing the condition from this ItemGroup means these .NET Framework references will now be included for all target frameworks. If this project ever targets non-.NET Framework versions in the future, these references may cause build errors or warnings since they're specific to .NET Framework.