[YogiOnCode]

Every pull request and every push to main now builds Clayo and runs every check on GitHub. A red run shows which check broke and which case inside it failed.

CI (.github/workflows/ci.yml)

• A windows job on windows-latest builds src/Clayo Debug and Release with -warnaserror, then runs scripts/checks.ps1.
• A newer push to the same branch cancels the run it replaces. NuGet packages are cached.
• Actions are pinned to a commit, as in release.yml. The token is read-only.
• release.yml is unchanged.

scripts/checks.ps1

• Runs every check in checks/, or only the ones you name (.\scripts\checks.ps1 status sessions), and exits with the number that failed. It behaves the same locally and on CI.
• A failing check prints its own output, including build errors, so the log says which case broke.
• -Core runs only the checks that target net10.0. There are none yet; they come with the Mac work (M3) and will also run on macOS.
• mascot.cs is left out. It renders PNGs to compare by eye, it isn't a pass/fail check.

Docs

• README: a CI badge.
• CONTRIBUTING.md: branch, build, scripts/checks.ps1, PR.

After merging

Make windows a required check on main in the ruleset, only once this PR's run is green.

Testing

• dotnet build and dotnet build -c Release with -warnaserror give 0 warnings and 0 errors.
• scripts/checks.ps1 passes all 19 checks in about 45s. Named runs, -Core and an unknown name behave as expected.
• A throwaway failing check and a throwaway check that doesn't compile each showed FAIL with their output, and the exit code was the failure count. Both were removed.
• The CI steps pass in a fresh clone with only tracked files.
• This PR's own run is the first CI run.