Add: logging system for debugging and audit trail

[AdityaDwiNugroho]

Implements comprehensive logging functionality (#3):

• Add log_message() function with timestamp formatting
• Implement log rotation when file exceeds 1MB
• Add ENABLE_LOGGING and LOG_PRIVACY config options
• Create 'log' command with --tail and --clear options
• Add logging to create, start, and stop operations
• Include privacy mode to avoid logging sensitive data
• Update README with logging documentation

All acceptance criteria met:

• Logging can be enabled/disabled via config
• Log file created in ~/.config/nm-hotspot/
• All major actions are logged with timestamps
• Log viewing and clearing commands implemented
• Log rotation functionality included
• Privacy-conscious with LOG_PRIVACY option

[github-actions]

Thanks for opening your first pull request in nm-hotspot-cli, @AdityaDwiNugroho.

A maintainer will review your contribution. Here's what happens next:

1. Automated checks will run
2. A maintainer will review your code
3. Changes may be requested
4. Once approved, your PR will be merged

Please ensure:

• Your code follows the project style guidelines
• You have tested your changes
• Documentation is updated if needed

Thank you for contributing.

[HiddenKeyDev]

Thanks for the contribution! Could you please address the ShellCheck errors before we proceed with the review?

[HiddenKeyDev]

LGTM! Great work on implementing the logging system. Merging now.