feat: scaffold headlamp-argocd-plugin with standard plugin structure

Adds the full plugin scaffold matching the Headlamp plugin pattern
(polaris, kube-vip, etc.):
- package.json with full devDependencies (Vitest, TypeScript, ESLint, Prettier)
- tsconfig.json, vitest.config.mts, vitest.setup.ts
- src/index.tsx with ArgoCDErrorBoundary and stub Applications route
- src/index.test.tsx smoke test to verify module importability
- CLAUDE.md documentation for future development
- .gitignore for node_modules/dist
- pnpm-lock.yaml pinned via packageManager field

ArtifactHub metadata already present (created by Hugh in PRI-186).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/index.test.tsx

@@ -0,0 +1,16 @@
+import React from 'react';
+import { describe, it, expect } from 'vitest';
+import { render } from '@testing-library/react';
+import '@testing-library/jest-dom';
+
+/**
+ * Minimal test to verify the plugin index module loads without throwing.
+ * Full component tests will be added in subsequent tasks.
+ */
+describe('ArgoCD Plugin Scaffold', () => {
+  it('index module is importable', async () => {
+    // Dynamic import to verify the module parses and exports correctly
+    const mod = await import('./index');
+    expect(mod).toBeDefined();
+  });
+});

src/index.tsx

@@ -0,0 +1,76 @@
+import {
+  registerRoute,
+  registerSidebarEntry,
+} from '@kinvolk/headlamp-plugin/lib';
+import { SectionBox, StatusLabel } from '@kinvolk/headlamp-plugin/lib/CommonComponents';
+import React from 'react';
+
+// --- Error boundary for plugin components ---
+
+interface ErrorBoundaryState {
+  error: string | null;
+}
+
+class ArgoCDErrorBoundary extends React.Component<
+  { children: React.ReactNode },
+  ErrorBoundaryState
+> {
+  state: ErrorBoundaryState = { error: null };
+
+  static getDerivedStateFromError(error: Error): ErrorBoundaryState {
+    return { error: error.message };
+  }
+
+  render() {
+    if (this.state.error) {
+      return (
+        <SectionBox title="ArgoCD Plugin Error">
+          <StatusLabel status="error">{this.state.error}</StatusLabel>
+        </SectionBox>
+      );
+    }
+    return this.props.children;
+  }
+}
+
+// --- Stub Applications List View ---
+
+function ArgoCDStubView() {
+  return (
+    <SectionBox title="ArgoCD Applications">
+      <StatusLabel status="info">Plugin scaffold — features coming soon.</StatusLabel>
+    </SectionBox>
+  );
+}
+
+// --- Sidebar entry ---
+
+registerSidebarEntry({
+  parent: null,
+  name: 'argocd',
+  label: 'ArgoCD',
+  url: '/argocd',
+  icon: 'mdi:git',
+});
+
+registerSidebarEntry({
+  parent: 'argocd',
+  name: 'argocd-overview',
+  label: 'Applications',
+  url: '/argocd',
+  icon: 'mdi:view-list',
+});
+
+// --- Routes ---
+
+registerRoute({
+  path: '/argocd',
+  sidebar: 'argocd-overview',
+  name: 'argocd',
+  exact: true,
+  component: () => (
+    <ArgoCDErrorBoundary>
+      <ArgoCDStubView />
+    </ArgoCDErrorBoundary>
+  ),
+});