Add all 23 GoF design pattern implementations

01-creational/abstract-factory/DarkTextField.java

@@ -0,0 +1,10 @@
+package abstractfactory;
+public class DarkTextField implements TextField {
+    private String value = "";
+    @Override
+    public void render() {
+        System.out.println("[Dark TextField] Dark gray background, light placeholder text");
+    }
+    @Override
+    public String getValue() { return value; }
+}