fix: revert to public/ brand assets — DS exports field blocks imports

The @cameleer/design-system package.json exports field doesn't include
assets/, causing production build failures. Copy PNGs to public/ and
reference via basePath until DS adds asset exports.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/auth/LoginPage.tsx

@@ -4,7 +4,6 @@ import { useAuthStore } from './auth-store';
 import { api } from '../api/client';
 import { config } from '../config';
 import { Card, Input, Button, Alert, FormField } from '@cameleer/design-system';
-import brandLogo from '@cameleer/design-system/assets/cameleer3-192.png';
 import styles from './LoginPage.module.css';
 
 interface OidcInfo {
@@ -132,7 +131,7 @@ export function LoginPage() {
       <Card className={styles.card}>
         <div className={styles.loginForm}>
           <div className={styles.logo}>
-            <img src={brandLogo} alt="" className={styles.logoImg} />
+            <img src={`${config.basePath}cameleer3-logo-192.png`} alt="" className={styles.logoImg} />
             cameleer3
           </div>
           <p className={styles.subtitle}>{subtitle}</p>