feat: implement bank account system with auditing and transaction log…

[jaydenellis]

Enhanced Bank ATM with SOLID Principles Implementation

Summary

Implemented SOLID principles enhancements to the Bank ATM simulator by adding inheritance hierarchy and Observer pattern for audit logging.

Changes Made

Option 1: SavingsAccount Implementation

• Created Account interface with core banking operations
• Added BaseAccount abstract class implementing template method pattern
• Extended SavingsAccount from BaseAccount with check transaction restrictions
• Updated CheckingAccount to extend BaseAccount for consistency
• Modified Customer class to support mixed account types

Option 4: AuditLog Integration

• Implemented Observer pattern with TransactionObserver interface
• Created AuditEntry data class for transaction records
• Added AuditLog class implementing TransactionObserver
• Integrated audit logging into BankAtm transaction methods
• Added observer management methods to ATM

SOLID Principles Demonstrated

• Single Responsibility: Each class has one clear purpose