refactor(banking-demo): introduce DemoApplication orchestrator and add controlled lifecycle management

- Replace DemoFactory with DemoApplication to centralize system setup, execution, and shutdown
- Move ExecutorService and ScheduledExecutorService lifecycle management into application layer
- Ensure proper shutdown sequence for worker and monitoring threads
- Simplify Main class to a minimal entry-point wrapper
- Improve clarity of execution flow: build → run → shutdown
- Prevent resource leakage by explicitly awaiting termination of thread pools

src/main/java/dev/banking/Main.java

@@ -1,17 +1,11 @@
 package dev.banking;
 
-import dev.banking.service.BankingSystem;
-import dev.banking.DemoFactory;
-
 /**
  * Entry point of the application.
  *
- * This class is provided for demonstration purposes only.
- *
  * IMPORTANT:
- * - Do NOT modify this file.
- * - This file is NOT used during grading.
- * - All grading is performed through the provided JUnit tests.
+ * - Do NOT modify this file in student assignment.
+ * - This is only a wrapper for running the demo.
  */
 public final class Main {
 
@@ -22,25 +16,19 @@ public final class Main {
 
         System.out.println("=================================");
         System.out.println(" Advanced Banking System");
-        System.out.println("=================================");
+        System.out.println("=================================\n");
 
         try {
 
-            BankingSystem bankingSystem =
-                    DemoFactory.createDemoSystem();
-
-            System.out.println("System initialized...");
-            System.out.println("Running simulation with concurrent workers...\n");
-
-//            bankingSystem.start();
+            DemoApplication.run();
 
             System.out.println("\n=================================");
-            System.out.println("Simulation completed successfully.");
+            System.out.println(" System finished successfully ");
             System.out.println("=================================");
 
         } catch (Exception e) {
 
-            System.err.println("\nUnexpected error occurred:");
+            System.err.println("Unexpected error occurred:");
             e.printStackTrace();
         }
     }