MSBuild on Windows compares solution-filter project paths against .sln entries as raw strings, so the forward-slash entries in TeamsISO.Windows.slnf / TeamsISO.Linux.slnf were being rejected (MSB5028) against the .sln's backslash entries. Linux dotnet normalizes separators so CI happened to be green. Switch the .sln to forward slashes so both platforms agree; Visual Studio accepts either form.
- TeamsISO.App: hand-rolled net8.0-windows WPF csproj since the WPF
template isn't shipped on linux-arm64 .NET SDK; UI is a placeholder
for Phase C.
- TeamsISO.Engine.IntegrationTests: cross-platform xunit project with a
skipped scaffold fact tagged [Trait("requires", "ndi")] for Phase B.
- TeamsISO.Linux.slnf: solution filter for non-Windows CI that excludes
the WPF project (which can only build on Windows).
