fix: use full-color brand PNGs for login dialog and sidebar

The SVG uses fill=currentColor (inherits text color). Switch to the
full-color PNG brand icons: 192px for login dialog, 48px for sidebar.

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

ui/src/auth/LoginPage.tsx

@@ -131,7 +131,7 @@ export function LoginPage() {
       <Card className={styles.card}>
         <div className={styles.loginForm}>
           <div className={styles.logo}>
-            <img src={`${config.basePath}camel-logo.svg`} alt="" className={styles.logoImg} />
+            <img src={`${config.basePath}cameleer3-logo-192.png`} alt="" className={styles.logoImg} />
             cameleer3
           </div>
           <p className={styles.subtitle}>{subtitle}</p>