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/nginx.conf

@@ -0,0 +1,38 @@
+server {
+    listen       80;
+    server_name  _;
+    root         /usr/share/nginx/html;
+    index        index.html;
+
+    # SPA fallback: serve index.html for all non-file routes
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # API proxy — target set via CAMELEER_API_URL env var (default: http://cameleer3-server:8081)
+    location /api/ {
+        proxy_pass         ${CAMELEER_API_URL};
+        proxy_set_header   Host $host;
+        proxy_set_header   X-Real-IP $remote_addr;
+        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
+        proxy_set_header   X-Forwarded-Proto $scheme;
+
+        # SSE support
+        proxy_buffering    off;
+        proxy_cache        off;
+        proxy_read_timeout 86400s;
+    }
+
+    # Caching for static assets
+    location /assets/ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+
+    # Health check
+    location /healthz {
+        access_log off;
+        return 200 "ok\n";
+        add_header Content-Type text/plain;
+    }
+}