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/auth/LoginPage.tsx

@@ -0,0 +1,61 @@
+import { type FormEvent, useState } from 'react';
+import { Navigate } from 'react-router';
+import { useAuthStore } from './auth-store';
+import styles from './LoginPage.module.css';
+
+export function LoginPage() {
+  const { isAuthenticated, login, loading, error } = useAuthStore();
+  const [username, setUsername] = useState('');
+  const [password, setPassword] = useState('');
+
+  if (isAuthenticated) return <Navigate to="/" replace />;
+
+  const handleSubmit = (e: FormEvent) => {
+    e.preventDefault();
+    login(username, password);
+  };
+
+  return (
+    <div className={styles.page}>
+      <form className={styles.card} onSubmit={handleSubmit}>
+        <div className={styles.logo}>
+          <svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+            <path d="M12 2C6.5 2 2 6.5 2 12s4.5 10 10 10 10-4.5 10-10S17.5 2 12 2" />
+            <path d="M12 6v6l4 2" />
+          </svg>
+          cameleer3
+        </div>
+        <div className={styles.subtitle}>Sign in to access the observability dashboard</div>
+
+        <div className={styles.field}>
+          <label className={styles.label}>Username</label>
+          <input
+            className={styles.input}
+            type="text"
+            value={username}
+            onChange={(e) => setUsername(e.target.value)}
+            autoFocus
+            autoComplete="username"
+          />
+        </div>
+
+        <div className={styles.field}>
+          <label className={styles.label}>Password</label>
+          <input
+            className={styles.input}
+            type="password"
+            value={password}
+            onChange={(e) => setPassword(e.target.value)}
+            autoComplete="current-password"
+          />
+        </div>
+
+        <button className={styles.submit} type="submit" disabled={loading || !username || !password}>
+          {loading ? 'Signing in...' : 'Sign In'}
+        </button>
+
+        {error && <div className={styles.error}>{error}</div>}
+      </form>
+    </div>
+  );
+}