[feat] Error Handling Enhancement

[san-ghun]

The error handling in tiny42.py could be improved. Currently, many operations silently fail or only print error messages. Consider:

• Creating custom exceptions for different error scenarios
• Implementing proper error propagation
• Adding more detailed error messages

Example implementation:

class Tiny42Error(Exception):
    """Base exception for tiny42 errors."""
    pass

class DockerEnvironmentError(Tiny42Error):
    """Raised when Docker environment is not properly configured."""
    pass

class WorkspaceError(Tiny42Error):
    """Raised when workspace-related issues occur."""
    pass