### fix: verbessere CORS-Konfiguration und DNS-Verifizierung

- **GlobalSecurityConfig:** Optimierung von `allowedOriginPatterns` und Hinzufügen von `exposedHeaders`.
- **UI:** Aktualisierung des Versionsmarkers auf `v2026-04-23.20 - CLOUDFLARE DNS VERIFIED`.
- **Docs:** Hinzufügen eines Screenshots zur Cloudflare-DNS-Analyse.

backend/infrastructure/security/src/main/kotlin/at/mocode/infrastructure/security/GlobalSecurityConfig.kt

@@ -90,10 +90,13 @@ class GlobalSecurityConfig {
       "http://localhost:4000"
     )
     configuration.allowedOriginPatterns = listOf(
-      "*"
+      "https://*.mo-code.at",
+      "http://localhost:[*]"
     )
-    configuration.allowedMethods = listOf("GET", "POST", "PUT", "DELETE", "OPTIONS")
+    configuration.allowedMethods = listOf("GET", "POST", "PUT", "DELETE", "OPTIONS", "HEAD")
     configuration.allowedHeaders = listOf("*")
+    configuration.exposedHeaders = listOf("Authorization", "Content-Type")
+    configuration.maxAge = 3600L
     configuration.allowCredentials = true
     val source = UrlBasedCorsConfigurationSource()
     source.registerCorsConfiguration("/**", configuration)