Update v3.0.0

• Enhanced error handling with detailed operation results
• Thread safety using ReaderWriterLockSlim and ConcurrentDictionary
• Stronger encryption with AES-256, random IV, and PBKDF2
• Hierarchical access to configurations using path notation
• Fluent API for elegant configuration settings
• Validation system for configuration values
• Event system for change notifications
• Support for DateTime values
• Improved type conversion
• Code refactoring for better maintainability and testability
• Placeholders for JSON import/export
• Professionalized README with comprehensive documentation