fix(helm): use yaml.stringify for Values viewer + cluster fix

[nadaverell]

Summary

The Helm release Values viewer used a hand-rolled JSON→YAML converter that emitted - on its own line for array-of-object items, then indented the object body by 2 extra levels. The result was broken rendering for any nested list-of-objects, e.g. Istio VirtualService:

http:
  -
    route:
      -
        destination:
          host: …

instead of the canonical:

http:
  - route:
      - destination:
          host: …

Replaces the custom serializer with yaml.stringify from the yaml v2 package — the same library Radar already uses for parsing, and the same approach Headlamp's Flux plugin takes. The only non-default option is lineWidth: 0, which disables line folding so long image tags / repo URLs / paths don't wrap mid-token.

While in the neighborhood, applied the same { lineWidth: 0 } option to the other five yaml.stringify call sites in InstallWizard.tsx and the GitOps detail page's safeStringifyYaml helper, which all silently inherited the 80-col default and had the same latent wrap bug.

Net change: −38 / +4 lines (ValuesViewer.tsx) plus one option added at six other sites. No new imports.

Test plan

• make tsc passes
• Helm > Values renders nested arrays correctly in prometheus chart (scrape_configs, relabel_configs)
• Sanity-checked yaml.stringify output against the Istio VirtualService case from the bug report
• Spot-check Install Wizard initial state for a chart with long image tags (no mid-tag wrapping)
• Spot-check GitOps detail page for an Argo Application with Helm values (no line wrap)

---

Note

Low Risk
Low risk UI-only change that affects how Helm/GitOps values are serialized for display/defaults; main risk is minor formatting differences in rendered YAML.

Overview
Fixes Helm values YAML rendering by replacing the hand-rolled JSON→YAML serializer in ValuesViewer.tsx with yaml.stringify, eliminating incorrect list-of-object formatting.

Also standardizes YAML output across the Helm install wizard and GitOps Helm-values display by passing lineWidth: 0 to yaml.stringify (via safeStringifyYaml and related call sites) to prevent mid-token line folding/wrapping.

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