Draft: feat: add optional local ephemeralregistry subchart

Plan

1. Bundle the optional local ephemeralregistry chart in the existing GitLab Runner review release, as requested by owner in the review thread.
2. Run local OCI push/pull/tag expiry through the parent release Helm hook before downstream Runner acceptance; share the required Runner cleanup lifecycle.
3. Preserve existing 4.225.0 pins and the upstream expiry-image digest; verify complete new-head CI, teardown and final DoD before review.

Shared-component follow-up — pending

Owner resolved the earlier generic-component review threads; those resolutions are preserved. The eight supplementary shell suites introduced under tests/ have been removed; the bundled Helm test hook and baseline suites remain. The separate scripts/ request and changed-source CI verification remain pending. Both later owner threads remain unresolved until the requested source cleanup and verification are complete. The earlier shared-component extraction is tracked in CI Tools #440; its final discovery absence is not being treated as an open blocker.

• Move scripts/helm-metrics-readiness.sh into the generic helm and review-helm components (request).
• Move scripts/helm-diagnostic-display.sh into those generic components (request).
• Move the Runner-local start/stop CI overrides into review-helm (start request, stop request).

The MR remains draft pending final reconciliation of the shared-component consumer follow-up and final DoD. Existing CI proves the unchanged source; owner thread resolution is recorded separately from implementation and CI verification.

Remaining plan

1. Deliver the generic helpers and lifecycle integration in CI Tools with behavior-focused regressions.
2. Adapt this consumer without changing its existing component version pins, registry image digest, chart location or single Runner/registry review lifecycle.
3. Verify complete changed-source root/child CI, owned Runner and namespace teardown, final diff and current-main rebase before returning to guarded review. The owner-resolved threads stay resolved.

Amended acceptance criteria

• Generic readiness and safe diagnostic display are provided by helm and review-helm.
• Generic start/stop integration lives in review-helm; redundant Runner-local overrides are removed.
• Existing pins, digest and shared review lifecycle remain unchanged.
• Changed-source regression execution, complete CI and owned-resource teardown are verified.
• Earlier generic-component review threads were resolved by owner.
• Remove the eight MR-added supplementary shell suites under tests/, retaining Helm-test coverage and baseline suites.
• Reconcile the separate scripts/ cleanup request without breaking Runner lifecycle/teardown.
• Verify complete CI for the changed source; earlier-source evidence below does not validate this cleanup.
• Shared-component consumer follow-up and the final Definition of Done are reconciled.

Previous validated amendment

Implemented in 113f425: removed the standalone registry review component and start/stop overrides; enabled ephemeralregistry in the actual Runner review values and enabled its Helm hooks. The standalone chart build/package remains available; it no longer creates a separate review environment. Updated the review guide and reviewed its rendered HTML.

The regression renders the actual parent review values and checks the registry Deployment, local Service URL and test hook. It also verifies a single Runner review lifecycle with Helm tests enabled. Baseline review values omit the registry/hook; the corrected configuration passes. All eleven local Bash suites and GitLab CI lint pass. Current-main rebase is a no-op; diff whitespace checks pass.

Exact source 113f425 now passes root CI, integration child, all 23 jobs and the required bridge. The eleven Bash suites execute the actual shared-review regression. The bundled registry hook proves OCI push/pull/tag expiry. Shared teardown uninstalls the release, removes owned Runner 57900979 and verifies namespace deletion. The complete amended 27-file diff and all five owner amendments are reconciled. Current-main rebase is a no-op and the diff whitespace check passes. Chart-local documentation, unchanged 4.225.0 pins and sidecar digest, single Runner review lifecycle, eleven executed Bash suites, local OCI expiry, downstream acceptance and owned-resource teardown meet the final DoD. The earlier amendment thread was resolved. The shared-component follow-up above still needs final source and CI reconciliation; owner has resolved its review threads and this MR remains draft pending final DoD.

Previous-source acceptance evidence (not current review readiness)

• Requested chart name/location and chart-local documentation retained.
• No separate registry review; registry is enabled in the Runner review release.
• Required local OCI/expiry hook enabled before Runner downstream acceptance.
• Existing component pins and upstream digest preserved without version upgrades.
• Baseline negative case, all eleven local Bash suites, CI lint and rendered documentation checked.
• Complete exact-new-head root/child CI and actual execution of the new regression verified.
• Live bundled registry push/pull/expiry and owned Runner/namespace cleanup verified for the new head.
• Reconcile the shared-component consumer follow-up and final DoD before guarded review.

Closes #20