feat(gateway)!: require explicit non-loopback control-ui origins

src/config/types.gateway.ts

@@ -70,6 +70,11 @@ export type GatewayControlUiConfig = {
   root?: string;
   /** Allowed browser origins for Control UI/WebChat websocket connections. */
   allowedOrigins?: string[];
+  /**
+   * DANGEROUS: Keep Host-header origin fallback behavior.
+   * Supported long-term for deployments that intentionally rely on this policy.
+   */
+  dangerouslyAllowHostHeaderOriginFallback?: boolean;
   /**
    * Insecure-auth toggle.
    * Control UI still requires secure context + device identity unless