argocd: Add Open in Argo CD Application action

[Joshna907]

Summary

This PR adds a safe Open in Argo CD action to the existing Argo CD Application detail header. The Argo icon opens the exact Application in the configured native Argo CD UI in a new browser tab.

Why

Headlamp provides Kubernetes-native visibility and operations. Argo CD's own UI remains the right place for advanced diffs, diagnostics, and resource actions. This gives operators a safe direct path from an Application in Headlamp to that same Application in Argo CD.

Changes

• Added optional status.controllerNamespace metadata and an Application getter.
• Reads only the argocd-cm ConfigMap using Headlamp's public ConfigMap API.
• Looks up the ConfigMap in status.controllerNamespace, falling back to the Application namespace.
• Shows the action only when argocd-cm.data.url is a valid absolute HTTP or HTTPS URL.
• Safely builds /applications/<namespace>/<name> URLs, preserving configured installation paths and encoding names.
• Rejects unsafe, malformed, relative, credential-bearing, or missing-host URLs.
• Opens the external UI with noopener,noreferrer.
• Documents the optional least-privilege ConfigMap permission and adds a fake local test manifest.

Validation

• Prettier formatting check passed.
• ESLint passed with zero warnings.
• TypeScript passed with no emit.
• All 6 test files and 45 tests passed.
• Production build passed.

Manual test

• Configured a local Argo CD UI URL.
• Confirmed the Argo icon appears beside Sync and Refresh on the Application detail page.
• Confirmed it opens the exact guestbook Application in the native Argo CD UI.
• Confirmed native Argo CD authentication, application tree, and advanced actions remain handled by Argo CD itself.

Permissions

The optional action requires only:

- apiGroups: [""]
  resources: ["configmaps"]
  resourceNames: ["argocd-cm"]
  verbs: ["get"]

When the ConfigMap is unavailable, forbidden, missing a URL, or contains an invalid URL, the action is simply hidden.

[Copilot]

Pull request overview

Adds a safe external link from Application details to the corresponding Argo CD UI page.

Changes:

• Resolves and validates the configured Argo CD URL.
• Adds the detail-header action with comprehensive tests.
• Documents optional RBAC and local testing configuration.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
argocd/test-files/deploy/argocd-cm.yaml	Adds mock UI configuration.
argocd/src/resources/application.ts	Exposes the controller namespace.
argocd/src/resources/application.test.ts	Tests the new accessor.
argocd/src/components/applications/openInArgoCD.tsx	Implements URL validation and external action.
argocd/src/components/applications/openInArgoCD.test.tsx	Tests URL safety and action behavior.
argocd/src/components/applications/Detail.tsx	Adds the action to Application details.
argocd/src/components/applications/Detail.test.tsx	Verifies header action integration.
argocd/README.md	Documents behavior, permissions, and testing.

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