fix(infra): release Helm charts for infra-scoped changes

Resolves no tracked issue.

Fixes the Helm chart release detection so chart-path changes with broader conventional scopes, such as infra or kura, trigger the automatic Helm publishing job.

The root cause was that the Helm component already filtered commits to chart paths, but infra/helm/cliff.toml only counted commits explicitly scoped as (helm). PR #11367 changed infra/helm/tuist/** with the subject feat(infra): support external PostgreSQL existing secrets, so release:check ignored it, helm-should-release stayed false, and the release-helm job never published a chart containing the change.

The chosen fix keeps the existing path-based component boundary as the source of truth and lets the Helm changelog parser accept normal conventional commit scopes for commits that already matched those paths. That avoids requiring every infra chart change to use a special (helm) scope while still keeping unrelated repository changes out of Helm releases.

The shared release:check script also no longer depends on Bash 4-only features, so the same release check can run from a local macOS worktree as well as Linux CI.

User impact: future chart changes under infra/helm/**/* and kura/ops/helm/kura/**/* will trigger the automatic Helm chart release as expected. In the current range, the check now selects helm@0.3.0, which includes the external PostgreSQL existing secret support.

How to test locally

• mise run release:check -- helm
• git cliff --include-path "infra/helm/**/*" --include-path "kura/ops/helm/kura/**/*" --config infra/helm/cliff.toml --repository . --bumped-version -- helm@0.2.1..HEAD
• git diff --check

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