Prevent wrong-platform native DLL from overriding Linux publish output

[viktor-shnaider]

Problem

dotnet publish -r linux-x64 produced a Windows PE32+ DLL instead of a Linux ELF binary.

The package's .targets file used hard-coded <ItemGroup> blocks that always copied runtimes/win-x64/native/ into every SDK project's bin/ output. SDK-style projects don't need this - NuGet resolves the correct runtimes/{rid}/native/ binary automatically at publish time. The forced copy overwrote the correct Linux binary with a Windows one before the publish collector ran.

Changes

.targets two fixes:

1. Replace three Platform-keyed <ItemGroup> blocks with a single that prefers $(RuntimeIdentifier) and falls back to a Platform → RID mapping.
2. Add '$(UsingMicrosoftNETSdk)' != 'true' to the <ItemGroup> condition. The manual copy is only needed for legacy .NET Framework consumers; SDK-style projects get native assets resolved automatically, and the copy was actively breaking cross-platform publishing.

.csproj direct-pack - fix broken paths in the !$(BuiltOnCI) pack items:

Reproduce (Linux / WSL)

  mkdir /tmp/repro && cd /tmp/repro
  dotnet new console
  dotnet add package FiftyOne.DeviceDetection.Hash.Engine.OnPremise --version 4.5.62  # pre-fix
  dotnet publish -r linux-x64 -c Release --self-contained false
  file bin/Release/net*/linux-x64/publish/FiftyOne.DeviceDetection.Hash.Engine.OnPremise.Native.dll
  # Before fix: PE32+ executable (DLL) (GUI), x86-64  ← wrong
  # After fix:  ELF 64-bit LSB shared object, x86-64  ← correct