perf(ci): accelerate CI with nuget caching, shallow clones, and split coverage

[spelech]

Summary

Optimizes CI and release workflows to significantly reduce GitHub Actions runner execution time and automate frontend lint/typecheck gates on PRs.

Optimizations

1. Parallel Lint & Typecheck Quality Gate: Added a fast concurrent job executing npm ci, npm run lint, and npx tsc --noEmit.
2. NuGet Caching: Enabled cache: true and cache-dependency-path in actions/setup-dotnet across ci.yml and release.yml.
3. Shallow Clones: Replaced full git clone with git clone --depth 1 for Avalonia.LayoutInspector.
4. Targeted Code Coverage: Runs Coverlet code coverage exclusively on ubuntu-latest and runs standard dotnet test on windows-latest, drastically reducing Windows CI duration.