sec: Sigstore signing, SBOM, Grype, CodeQL + docs

[Pyronewbic]

Summary

• Cosign keyless container signing via GitHub OIDC, deploy by image digest
• Syft SBOM generation (SPDX JSON) as build artifact
• Grype vulnerability scanning with SARIF to GitHub Security tab
• CodeQL SAST on PRs + weekly schedule
• Binary Authorization on both Cloud Run services (DRYRUN audit mode)
• Terraform CI: tfvars from GitHub secrets, Docker auth for cosign
• Kaniko pinned v1.23.2, --reproducible, dual tags
• Docs: CHANGELOG, README security section, internals security pipeline table

Type

• Infra / config
• Docs / tests

Endpoints

None

Checks

• yarn test:unit passes
• terraform validate passes

Infrastructure

• New GCP APIs: Binary Authorization, Container Analysis
• New IAM roles on deploy SA: binaryauthorization.policyEditor, serviceusage.serviceUsageAdmin
• New GitHub secret: ALERT_EMAIL (for Terraform tfvars)
• Binary Auth policy: DRYRUN_AUDIT_LOG_ONLY
• Terraform auto-applies on merge (terraform/ path filter)

Frontend impact

None

Deploy notes

First deploy will run the full signing + scanning pipeline. Binary Auth is DRYRUN so no blocking risk. Verify cosign signing succeeds, then switch to ALWAYS_DENY in a future PR.

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.