Salesforce CI/CD with GitHubActions

I need my Salesforce development workflow fully automated through GitHub Actions CI. The goal is to move from manual deployments to a reliable CI/CD pipeline that covers every step—from code commit to production release—while following Salesforce best practices (SFDX, scratch orgs, unlocked packages).

Here is what I want to accomplish:

• Pipeline configuration: create or refine .gitlab-ci.yml so that feature branches trigger scratch-org builds, run Apex tests, static code analysis, and package creation.
• Environment setup: connect GitLab runners to my Salesforce orgs, manage authentication with JWT-based connections, and handle secrets securely in GitLab variables.
• Automated testing: ensure unit tests run in scratch orgs on every merge request, with code-coverage gates that block merges if thresholds are not met.

Acceptance is met when a merge to main automatically:
1. Spins up a scratch org, installs dependencies, and passes all tests.
2. Generates an unlocked package or deployment artifact.
3. Promotes the artifact to a staging sandbox with change-set validation.
4. Provides clear success/failure feedback inside GitLab.

You’re free to leverage plugins such as sfdx-git-delta or any GitHub Actions shared runners as long as the solution remains maintainable and documented. Please keep the pipeline script and any helper scripts inside the repo and add concise README notes so my team can operate it after hand-off.