feat: add advanced multithreading banking system skeleton

src/main/java/dev/banking/DemoFactory.java

@@ -0,0 +1,55 @@
+package dev.banking;
+
+import dev.banking.service.BankingSystem;
+
+/**
+ * Creates a ready-to-run demonstration environment.
+ *
+ * Students do not need to modify this class.
+ */
+public final class DemoFactory {
+
+    private DemoFactory() {
+    }
+
+    /**
+     * Builds a fully configured banking simulation system.
+     *
+     * This includes:
+     * - Bank accounts
+     * - Transaction stream generator / loader
+     * - ExecutorService (thread pool)
+     * - Transaction processor
+     * - Live monitoring system
+     *
+     * @return configured BankingSystem instance
+     */
+    public static BankingSystem createDemoSystem() {
+
+        /*
+         * TODO (Instructor Implementation Only)
+         *
+         * Example responsibilities:
+         *
+         * 1. Create bank accounts:
+         *    - Account(1, 1000)
+         *    - Account(2, 2000)
+         *    - Account(3, 1500)
+         *
+         * 2. Create transaction list or stream
+         *
+         * 3. Initialize ExecutorService:
+         *    Executors.newFixedThreadPool(n)
+         *
+         * 4. Create TransactionProcessor
+         *
+         * 5. Create BankingSystem and inject dependencies
+         *
+         * 6. Attach LiveMonitor (optional)
+         */
+
+        throw new UnsupportedOperationException(
+                "Instructor implementation required."
+        );
+    }
+}