Refactor CI workflow for linting and building steps

[chrisreddington]

Separate linting and building steps in the CI workflow and utilize an environment variable for the Go version. This improves clarity and maintainability of the CI process.

[Copilot]

Pull Request Overview

This PR refactors the CI workflow by splitting linting and build/test into separate jobs and centralizing the Go version in an environment variable.

• Introduce a top-level GO_VERSION env var for the Go version
• Create a dedicated lint job and a separate build-and-test job
• Update all actions/setup-go steps to use ${{ env.GO_VERSION }}

Comments suppressed due to low confidence (1)

.github/workflows/ci.yml:61

• The Test step is still indented under the original job and not inside the new build-and-test job's steps. Move and re-indent it under build-and-test so that tests run as part of the build/test job.

- name: Test