fix: add ServerUtil.java

Author: airtouch97

src/client/java/com/lnlfly/util/ServerUtil.java

@@ -0,0 +1,24 @@
+package com.lnlfly.util;
+
+import com.lnlfly.config.ModConfig;
+
+public class ServerUtil {
+    public static String normalizeHost(String address) {
+        if (address == null) return "";
+        String value = address.trim();
+        int colon = value.indexOf(':');
+        if (colon > 0 && value.indexOf(']') < 0) {
+            return value.substring(0, colon);
+        }
+        return value;
+    }
+
+    public static boolean isTargetServer(String address) {
+        String target = ModConfig.get().targetServerAddress;
+        if (target == null) return false;
+
+        String targetHost = normalizeHost(target);
+        String host = normalizeHost(address);
+        return !targetHost.isEmpty() && targetHost.equalsIgnoreCase(host);
+    }
+}