Add React UI with Execution Explorer, auth, and standalone deployment

- Scaffold Vite + React + TypeScript frontend in ui/ with full design
  system (dark/light themes) matching the HTML mockups
- Implement Execution Explorer page: search filters, results table with
  expandable processor tree and exchange detail sidebar, pagination
- Add UI authentication: UiAuthController (login/refresh endpoints),
  JWT filter handles ui: subject prefix, CORS configuration
- Shared components: StatusPill, DurationBar, StatCard, AppBadge,
  FilterChip, Pagination — all using CSS Modules with design tokens
- API client layer: openapi-fetch with auth middleware, TanStack Query
  hooks for search/detail/snapshot queries, Zustand for state
- Standalone deployment: Nginx Dockerfile, K8s Deployment + ConfigMap +
  NodePort (30080), runtime config.js for API base URL
- Embedded mode: maven-resources-plugin copies ui/dist into JAR static
  resources, SPA forward controller for client-side routing
- CI/CD: UI build step, Docker build/push for server-ui image, K8s
  deploy step for UI, UI credential secrets

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

ui/src/router.tsx

@@ -0,0 +1,24 @@
+import { createBrowserRouter, Navigate } from 'react-router';
+import { AppShell } from './components/layout/AppShell';
+import { ProtectedRoute } from './auth/ProtectedRoute';
+import { LoginPage } from './auth/LoginPage';
+import { ExecutionExplorer } from './pages/executions/ExecutionExplorer';
+
+export const router = createBrowserRouter([
+  {
+    path: '/login',
+    element: <LoginPage />,
+  },
+  {
+    element: <ProtectedRoute />,
+    children: [
+      {
+        element: <AppShell />,
+        children: [
+          { index: true, element: <Navigate to="/executions" replace /> },
+          { path: 'executions', element: <ExecutionExplorer /> },
+        ],
+      },
+    ],
+  },
+]);