Add creational patterns, Interpreter; remove scripts; update README

01-creational/singleton/Main.java

@@ -0,0 +1,19 @@
+package singleton;
+
+public class Main {
+    public static void main(String[] args) {
+        System.out.println("=== Singleton Pattern Demo ===\n");
+
+        DatabaseConnection c1 = DatabaseConnection.getInstance();
+        DatabaseConnection c2 = DatabaseConnection.getInstance();
+        DatabaseConnection c3 = DatabaseConnection.getInstance();
+
+        System.out.println("\nAll three references same instance? " + (c1 == c2 && c2 == c3));
+
+        System.out.println(c1.executeQuery("SELECT * FROM users"));
+        System.out.println(c2.executeQuery("SELECT * FROM orders"));
+        System.out.println(c3.executeQuery("SELECT COUNT(*) FROM products"));
+
+        System.out.println("\nTotal queries: " + c1.getQueryCount());
+    }
+}