feat: replace icons with brand assets from design-system v0.1.32

- Replace favicon SVG with official camel-logo.svg from design-system
- Add PNG favicons (32px, 192px) with proper link tags in index.html
- Replace sidebar logo with 48px brand icon (cameleer-logo-48.png)
- Replace sign-in page logo with 48px brand icon
- Permit favicon PNGs in SecurityConfig

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

src/main/java/net/siegeln/cameleer/saas/config/SecurityConfig.java

@@ -45,7 +45,7 @@ public class SecurityConfig {
                         .requestMatchers("/api/config").permitAll()
                         .requestMatchers("/", "/index.html", "/login", "/callback",
                                 "/environments/**", "/license", "/admin/**").permitAll()
-                        .requestMatchers("/_app/**", "/favicon.ico", "/favicon.svg", "/logo.svg", "/logo-dark.svg").permitAll()
+                        .requestMatchers("/_app/**", "/favicon.ico", "/favicon.svg", "/favicon-32.png", "/favicon-192.png", "/logo.svg", "/logo-dark.svg").permitAll()
                         .anyRequest().authenticated()
                 )
                 .oauth2ResourceServer(oauth2 -> oauth2.jwt(jwt ->