feat: UI/UX redesign for MCP Apps - 3 new apps + enhanced existing (#583)

Add workflow-list, execution-history, and health-dashboard apps.
Redesign operation-result with operation-aware headers, detail panels,
and copy-to-clipboard. Fix React hooks violations in validation-summary
and execution-history (useMemo after early returns). Add local preview
harness for development. Update tests for 5-app config.

Conceived by Romuald Członkowski - www.aiadvisors.pl/en

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

ui-apps/src/apps/execution-history/main.tsx

@@ -0,0 +1,8 @@
+import React from 'react';
+import { createRoot } from 'react-dom/client';
+import App from './App';
+
+const root = document.getElementById('root');
+if (root) {
+  createRoot(root).render(<App />);
+}