Fix type alias heritage references

[Widthdom]

Summary

• Expand TypeScript and Swift alias-mediated heritage type references to the underlying target type.
• Respect scoped alias shadowing, type/generic parameter shadowing, and suppress alias type parameters during generic/function alias expansion.
• Add changelog fragment for Kind not propagated through type alias indirection #1976.

Validation

• dotnet test tests/CodeIndex.Tests/CodeIndex.Tests.csproj --filter "FullyQualifiedName~ReferenceExtractorTests" -p:UseSharedCompilation=false
• dotnet run --project tools/CodeIndex.Changelog -- check
• dotnet ./src/CodeIndex/bin/Debug/net8.0/cdidx.dll status --check --json
• Codex adversarial review performed; blocking findings were fixed during iteration.

Fixes #1976