Fix .NET SDK version pin and add CI workflow

[Copilot]

global.json pinned SDK 10.0.201 which doesn't exist in the environment, making dotnet entirely non-functional. No CI pipeline existed to catch this or future regressions.

Changes

• global.json — bump pinned version 10.0.201 → 10.0.102 (latest available .NET 10 SDK); rollForward: latestFeature unchanged
• .github/workflows/ci.yml — new GitHub Actions workflow: restore → build → test on every push/PR to main, scoped to contents: read

[Copilot]

Pull request overview

Fixes a broken .NET SDK pin that prevented dotnet from working, and introduces a basic GitHub Actions CI pipeline to restore/build/test on pushes and PRs targeting main.

Changes:

• Update global.json SDK version pin from 10.0.201 to 10.0.102.
• Add a new GitHub Actions workflow to run dotnet restore, dotnet build, and dotnet test on ubuntu-latest.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
global.json	Updates the pinned .NET SDK version to a working version.
.github/workflows/ci.yml	Adds CI workflow to automatically restore/build/test on pushes/PRs to main.

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[Copilot]

The CI installs .NET using dotnet-version: '10.0.x', which can drift from the pinned global.json SDK (10.0.102). That reduces reproducibility and can mask SDK-specific regressions. Consider installing the exact SDK from global.json (e.g., global-json-file: global.json) or pinning dotnet-version to 10.0.102 so local and CI builds use the same toolchain.

Suggested change

	dotnet-version: '10.0.x'
	global-json-file: global.json