Add PR GitHub Actions workflow to build WinUI and run Core tests on Windows

[bkaankose]

Motivation

• Add CI validation for pull requests that builds the WinUI app and runs core unit tests on Windows to catch regressions early.
• Ensure PRs (non-draft) exercise the Windows-specific WinUI build and the shared Core test suites before review.

Description

• Add a new workflow file /.github/workflows/pr-winui-build.yml that triggers on pull_request events (opened, synchronize, reopened, ready_for_review).
• Create a job build-winui-and-core-tests that runs on windows-latest and only executes for non-draft PRs via if: github.event.pull_request.draft == false.
• The job checks out the repo with actions/checkout@v4, sets up the .NET SDK with actions/setup-dotnet@v4 (dotnet-version: 10.0.x), restores and builds the Wino.Mail.WinUI/Wino.Mail.WinUI.csproj using dotnet restore and dotnet build, and then restores and runs all *Core*.Tests.csproj projects found recursively using PowerShell and dotnet test.

Testing

• No automated tests were executed as part of this change; the added workflow will run the WinUI build and Core test projects on subsequent non-draft PRs.

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Codex Task

[github-actions]

Core test results

55 tests   45 ✅  3s ⏱️
 1 suites  10 💤
 1 files     0 ❌

Results for commit 2751dfe.

♻️ This comment has been updated with latest results.