Add definition update and update-chart commands

[omattsson]

Summary

There's no stackctl definition update or stackctl definition update-chart command. Updating chart configs (default_values, chart_path, deploy_order, ingress hosts, etc.) requires direct curl to the backend API.

Commands needed

• stackctl definition update <name|id> — update definition metadata (name, description, default_branch)
• stackctl definition update-chart <definition> <chart-id> — update a chart config's default_values, chart_path, chart_version, deploy_order
  • Support --file values.yaml to set default_values from a file
  • Support --set key=value for individual value changes
  • Must preserve unspecified fields (chart_path, deploy_order, etc.) — current backend PUT replaces all fields, so the CLI must GET first and merge

Context

When updating only default_values via the PUT endpoint, all other fields (chart_path, deploy_order) are reset to zero values if not included in the request body. This caused a deploy failure when chart_path was accidentally cleared. The CLI should handle this by fetching the current config and merging changes.

Current workaround

curl -X PUT ".../api/v1/stack-definitions/$DEF/charts/$CHART_ID" \
  -H "Content-Type: application/json" \
  -d '{"chart_name":"kvk-core","chart_path":"/charts/kvk-core","chart_version":"0.2.0","deploy_order":6,"default_values":"..."}'