chore(scale-set): docs and workflows changes

[edersonbrilhante]

Description

Adds the documentation, CI, release, and integration-test support needed to validate and publish the GitHub Actions scale-set service introduced by #5300.

This PR includes:

• Dependabot coverage and grouping for GitHub Actions, Lambda dependencies, the scale-set service container, MiniStack, and documentation dependencies.
• Lambda CI coverage for formatting, linting, tests, distribution builds, multi-architecture scale-set container builds, and an isolated container smoke test. The smoke test runs the image with a read-only filesystem, dropped capabilities, no-new-privileges, and no network access, then validates the controller health response.
• A MiniStack ECS/MockServer integration test that builds and pushes the scale-set image to the local registry, applies the multi-runner-scale-set example, validates the rendered SSM configuration and ECS task definition, exercises GitHub App and scale-set protocol requests, verifies runner launch and registration, changes the minimum capacity to zero, verifies scale-down and termination, and cleans up the deployment.
• Pinned MockServer expectations and MiniStack fixtures for installation-token exchange, runner registration, scale-set discovery and label updates, JIT configuration generation, message-session creation, polling, and cleanup.
• Release workflow support for publishing the multi-architecture scale-set service image to GHCR with an SBOM, build provenance, and registry attestation. Release notes now include the immutable image digest and attestation information alongside Lambda artifact attestations.
• Security documentation describing the scale-set image provenance and the gh attestation verify command for production image verification.

Test Plan

• Lambda CI runs the repository format, lint, test, and build checks and builds the scale-set image for linux/amd64 and linux/arm64.
• The container smoke test validates the hardened image independently of AWS or GitHub.
• The MiniStack workflow runs the scale-set ECS/MockServer smoke test with pinned MiniStack and MockServer versions.
• git diff --check and the changed-file scope were verified for this follow-up branch.

Related Issues

• Follow-up to feat(scale-set): add service controller #5300.
• Exercises the Terraform scale-set deployment from feat(scale-set): add scale set orchestration in Terraform #5299.
• Includes the scale-set service smoke-test work from test(scale-set): run service container smoke test #5375.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

OpenSSF Scorecard

Package	Version	Score	Details
actions/actions/attest	1e69f48acb82d1966a394da916b4c1698aa569d6	Unknown	Unknown
actions/docker/build-push-action	53b7df96c91f9c12dcc8a07bcb9ccacbed38856a	🟢 7.5	Details Check Score Reason Security-Policy 🟢 9 security policy file detected Binary-Artifacts 🟢 10 no binaries found in the repo Code-Review 🟢 10 all changesets reviewed Maintained 🟢 10 30 commit(s) and 7 issue activity found in the last 90 days -- score normalized to 10 Dangerous-Workflow 🟢 10 no dangerous workflow patterns detected Token-Permissions ⚠️ 0 detected GitHub workflow tokens with excessive permissions CII-Best-Practices ⚠️ 0 no effort to earn an OpenSSF best practices badge detected Fuzzing ⚠️ 0 project is not fuzzed License 🟢 10 license file detected Branch-Protection ⚠️ -1 internal error: error during branchesHandler.setup: internal error: githubv4.Query: Resource not accessible by integration Signed-Releases ⚠️ -1 no releases found Packaging 🟢 10 packaging workflow detected Pinned-Dependencies 🟢 7 dependency not pinned by hash detected -- score normalized to 7 SAST 🟢 9 SAST tool detected but not run on all commits
actions/docker/login-action	dbcb813823bdd20940b903addbd779551569679f	🟢 8.5	Details Check Score Reason Code-Review 🟢 10 all changesets reviewed Security-Policy 🟢 9 security policy file detected Maintained 🟢 10 30 commit(s) and 0 issue activity found in the last 90 days -- score normalized to 10 Binary-Artifacts 🟢 10 no binaries found in the repo Dangerous-Workflow 🟢 10 no dangerous workflow patterns detected Token-Permissions 🟢 10 GitHub workflow tokens follow principle of least privilege CII-Best-Practices ⚠️ 0 no effort to earn an OpenSSF best practices badge detected Fuzzing ⚠️ 0 project is not fuzzed License 🟢 10 license file detected Signed-Releases ⚠️ -1 no releases found Branch-Protection ⚠️ -1 internal error: error during branchesHandler.setup: internal error: githubv4.Query: Resource not accessible by integration Pinned-Dependencies 🟢 6 dependency not pinned by hash detected -- score normalized to 6 Packaging 🟢 10 packaging workflow detected SAST 🟢 9 SAST tool detected but not run on all commits
actions/docker/setup-buildx-action	37fe631027851001ddb9b187196cc803df7f5f0e	🟢 8.6	Details Check Score Reason Maintained 🟢 10 30 commit(s) and 3 issue activity found in the last 90 days -- score normalized to 10 Security-Policy 🟢 9 security policy file detected Code-Review 🟢 10 all changesets reviewed Binary-Artifacts 🟢 10 no binaries found in the repo Dangerous-Workflow 🟢 10 no dangerous workflow patterns detected Token-Permissions 🟢 10 GitHub workflow tokens follow principle of least privilege CII-Best-Practices ⚠️ 0 no effort to earn an OpenSSF best practices badge detected Fuzzing ⚠️ 0 project is not fuzzed License 🟢 10 license file detected Branch-Protection ⚠️ -1 internal error: error during branchesHandler.setup: internal error: githubv4.Query: Resource not accessible by integration Signed-Releases ⚠️ -1 no releases found Pinned-Dependencies 🟢 7 dependency not pinned by hash detected -- score normalized to 7 Packaging 🟢 10 packaging workflow detected SAST 🟢 10 SAST tool is run on all commits
actions/docker/setup-qemu-action	96fe6ef7f33517b61c61be40b68a1882f3264fb8	🟢 8.4	Details Check Score Reason Security-Policy 🟢 9 security policy file detected Binary-Artifacts 🟢 10 no binaries found in the repo Maintained 🟢 10 30 commit(s) and 1 issue activity found in the last 90 days -- score normalized to 10 Code-Review 🟢 10 all changesets reviewed Packaging ⚠️ -1 packaging workflow not detected Dangerous-Workflow 🟢 10 no dangerous workflow patterns detected Token-Permissions 🟢 10 GitHub workflow tokens follow principle of least privilege CII-Best-Practices ⚠️ 0 no effort to earn an OpenSSF best practices badge detected Fuzzing ⚠️ 0 project is not fuzzed License 🟢 10 license file detected Branch-Protection ⚠️ -1 internal error: error during branchesHandler.setup: internal error: githubv4.Query: Resource not accessible by integration Signed-Releases ⚠️ -1 no releases found Pinned-Dependencies 🟢 5 dependency not pinned by hash detected -- score normalized to 5 SAST 🟢 10 SAST tool is run on all commits

Scanned Files

• .github/workflows/release.yml