Keep CodeQL c-cpp analysis buildless

[Copilot]

The Analyze (c-cpp) CodeQL job regressed by switching to autobuild, which caused CodeQL to invoke the repository root Makefile instead of performing analysis directly. That path pulled in Python lint/test targets and failed before C/C++ analysis could run.

• Workflow fix

  • Restore the c-cpp matrix entry in .github/workflows/codeql.yml to build-mode: none
  • Update the workflow comment to reflect that the C/C++ lane is intentionally buildless

• Regression coverage

  • Add a focused test in tests/test_codeql_workflow_paths_ignore.py that asserts the c-cpp CodeQL lane remains on build-mode: none
  • This guards against reintroducing autobuild on a repository whose root build entrypoint is not a valid C/C++ build

• Behavioral change

  • The CodeQL workflow no longer attempts to run the repo-wide make path for c-cpp
  • The lane stays aligned with the repository’s prior working CodeQL configuration

- language: c-cpp
  build-mode: none
  os: ubuntu-latest
  timeout-minutes: 360

[Copilot]

@Bryan-Roe Unfortunately, I hit an error while trying to use the custom Copilot setup steps configured for this repository and had to close this PR. The error I am seeing is:

no `copilot-setup-steps` job found in your `copilot-setup-steps.yml` workflow file. Please ensure you have a single job named `copilot-setup-steps`. For more details, see https://gh.io/copilot/actions-setup-steps

Once you or someone with the necessary access fixes the problem, please unassign and then reassign issue #0 to me and I'll retry. Thanks!

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[Copilot]

Pull request overview

This PR restores the CodeQL c-cpp analysis lane to be intentionally buildless (build-mode: none) to avoid autobuild invoking the repository root Makefile and failing before C/C++ analysis can run.

Changes:

• Switch the CodeQL c-cpp matrix entry back to build-mode: none.
• Update the workflow header comment to reflect the buildless C/C++ lane intent.
• Add a unit test asserting the c-cpp lane stays buildless (regression guard).

Reviewed changes

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

File	Description
.github/workflows/codeql.yml	Restores c-cpp lane to build-mode: none and updates documentation comment accordingly.
tests/test_codeql_workflow_paths_ignore.py	Adds a regression test ensuring the c-cpp CodeQL lane remains buildless and refactors an assertion for formatting.