Fix all NU1605 errors: suppress via Directory.Build.props instead of per-package pins
NCalc2 -> Antlr4 -> Antlr4.Runtime -> NETStandard.Library 1.6.0 triggers 6+
NU1605 downgrade warnings on linux-x64 publish (System.IO.FileSystem.Primitives,
System.Text.Encoding.Extensions, System.Diagnostics.Tracing, Microsoft.Win32.Primitives,
System.IO.FileSystem, System.Net.Primitives). All are harmless — .NET 8 supplies
these natively. Directory.Build.props suppresses NU1605 solution-wide cleanly.
Removes the individual System.Runtime.InteropServices pin added in previous commit.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
spouliot
cf07356147