Add tool to retrieve values.yaml from Helm chart

[PraneethShetty626]

It would be valuable to introduce a new MCP tool, helm_values, that allows users (and agents) to fetch the values.yaml from a specified Helm chart. This would support both the default chart values and user-overridden values, and allow version selection.

Motivation
Currently, there’s no built-in way in the MCP server to directly retrieve a chart’s configuration options before installing or upgrading it. Having such a capability would:

• Improve automation in workflows that need to inspect Helm charts programmatically.
• Enhance transparency by letting users review available configuration parameters.
• Reduce errors by allowing validation of chart values prior to deployment.

This is particularly useful in CI/CD pipelines, GitOps flows, and automation scripts where understanding configurable parameters is crucial.

Proposed Solution

• Add a new tool: helm_values.

• Support both local chart references and OCI registry charts.

• Allow version selection for charts stored in registries.

• Return chart values as structured YAML or JSON for programmatic consumption.

[PraneethShetty626]

cc: @manusa

Please review the implementation for the above feature request.

PR: #268

This PR introduces the helm_values tool to fetch values.yaml from a Helm chart (local or OCI), with support for version selection and full test coverage.