add trivy scanning

[MonicaG]

Add trivy to build docker image
Upload results to the security tab in GitHub

[github-advanced-security]

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[Copilot]

Pull Request Overview

Adds Trivy vulnerability scanning into the Docker image build pipeline and uploads scan results to GitHub’s Security tab.

• Introduce a scheduled workflow triggering the reusable build that now includes Trivy scanning
• Update the reusable build to grant security-events: write, tag images with the raw ref name, run Trivy, and upload SARIF results
• Propagate security-events: write permission to other build-update workflows

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
.github/workflows/scheduled.yaml	New scheduled workflow dispatching the reusable build workflow
.github/workflows/build.yaml	Added security-events permission, raw tagging, Trivy scan + upload steps
.github/workflows/build-update-gitops.yaml	Propagate security-events: write permission
.github/workflows/build-update-gitops-pr-branch.yaml	Propagate security-events: write permission

Comments suppressed due to low confidence (3)

.github/workflows/build.yaml:65

• If your SARIF template lives in this repository, use a relative path (e.g., ./contrib/sarif.tpl) instead of the @-prefixed syntax, which refers to files inside the action itself.

          template: '@/contrib/sarif.tpl'

.github/workflows/build.yaml:70

• [nitpick] Consider using the dedicated actions/upload-sarif@v3 action for uploading SARIF files—it's lighter-weight and focused solely on uploading results.

        uses: github/codeql-action/upload-sarif@v3

.github/workflows/build.yaml:61

• Add an exit-code: 1 option under the Trivy action’s with block so the build fails automatically when high or critical vulnerabilities are detected.

        with: