Built-in plugin: Helm chart versioning and publishing

[mwaldheim]

Goal

Automate Helm chart version bumping and publishing to OCI or ChartMuseum registries.

Tasks

• Update �ersion and �ppVersion in Chart.yaml
• Package chart with helm packagen- [ ] Push to OCI registry (GHCR, ECR, etc.) via helm pushn- [ ] Push to ChartMuseum via REST API
• Update index.yaml for GitHub Pages-based repos
• Support multiple charts in one repo (monorepo-aware)