fix: declare the package licence

[jcant0n]

Every push to nuget.org warns License missing, and the published package carries no licence expression — so nuget.org shows nothing where the licence link belongs and a compliance scanner has nothing to read.

EvergineTeam/WebGPU.NET#24 fixed this across the eight repositories that existed on 8 August. This one was created afterwards and missed the sweep. Companion PRs go out to the other three in the same position.

  <RepositoryUrl>https://github.com/EvergineTeam/Thorvg.NET</RepositoryUrl>
+ <PackageLicenseExpression>MIT</PackageLicenseExpression>
  <PackageIcon>icon.png</PackageIcon>

MIT describes the binding code, which is what the expression is for. The native library's own licence is unaffected, and its notice already travels with the binaries — nothing to add there.

Only the project that publishes a package is touched; the generator, demos and tests are left alone. There is no Directory.Build.props in this repository, so the csproj is the only place this can be declared.

Verified, not assumed

Packed locally with the .NET 10 SDK and opened the .nupkg:

nuspec licence : <license type="expression">MIT</license>
notice files   : (unchanged, still at the package root)

Byte hygiene checked too — no BOM introduced, LF preserved, tabs preserved. That is the mistake WebGPU.NET#24 had to correct in its own second commit.

🤖 Generated with Claude Code

[github-actions]

API gate: additive

Every symbol that existed still exists, unchanged. Nothing that compiled before stops compiling.

Target framework	Added	Removed
net10.0	+0	-0

_{Enum and constant values are part of the measured surface: a renumbering keeps compiling and sends the wrong number to the driver, so it counts as a removal.}