Add all 23 GoF design pattern implementations

01-creational/abstract-factory/Main.java

@@ -0,0 +1,16 @@
+package abstractfactory;
+
+// Entry point: the ONLY place that knows the theme
+public class Main {
+    public static void main(String[] args) {
+
+        // Production: read theme from config or OS preference
+        String theme = System.getProperty("app.theme", "light");
+        UIFactory factory = "dark".equals(theme) ? new DarkThemeFactory() : new LightThemeFactory();
+
+        Application app = new Application(factory);
+        app.buildUI();
+        app.render();
+        app.simulateSubmit();
+    }
+}