feat(manager): share OCI Helm chart resolution across managers

[secustor]

Changes

Adds getOciChartDep() to lib/modules/manager/helmv3/oci.ts and uses it in every manager that resolves Helm charts stored in OCI registries: argocd, fleet, flux, helmfile, helmsman, helmv3, kustomize, sveltos, terraform (helm_release) and vendir.

The helper strips the oci:// prefix and a trailing slash, resolves registryAliases through the dockerfile manager's getDep(), and returns the docker datasource, the packageName and pinDigests: false. The version fields these managers update cannot carry a digest: Helm only accepts one inside the OCI reference (chart@sha256:..., helm/helm#12690) and Flux HelmCharts take semver only, so a pin attempt failed in auto-replace with "Digest is not updated". Each manager keeps its own depName convention.

Until now every manager carried its own copy of this logic and the copies disagreed, so this PR also changes behaviour:

• pinDigests: false was only set by fleet, helmv3, kustomize and vendir. argocd, flux, helmfile, helmsman, sveltos and terraform now set it as well, so pinDigests: true no longer produces failing pin attempts. For argocd (already excluded by the docker:pinDigests preset) and terraform (manager default pinDigests: false) the dep-level flag only matters when pinDigests: true is set explicitly.
• registryAliases were ignored for OCI charts in argocd, helmfile (oci:// charts and oci: true repositories) and helmsman. They now apply the same way as for container images. The registryAliases docs and the argocd and helmsman readmes mention this.
• terraform joined repository and chart with url-join, which turns oci://registry.example.com:5000/charts into registry.example.com://5000/charts/<chart>. The port is kept now.
• fleet produced currentValue: 'undefined' for OCI charts without a version. Such charts are now skipped with unspecified-version, like charts from classic repositories.

Context

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• This closes an existing Issue, Closes: #
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Claude Code (Claude Fable 5.1) wrote the code, tests and documentation changes, starting from an audit of the duplicated OCI chart handling across managers.

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