Add functionality to parse and execute commands for adding/removing service monitors and shutting down the watchdog. The ExecuteCommand function now handles "monitor.add", "monitor.remove" and "watchdog.shutdown" commands by interacting with the monitor package and system operations.
Implement basic watchdog service for Linux systemd with:
- Configuration loading
- Logging system with database support
- WebSocket log broadcasting
- TCP server for agent communication
- Project setup with Go modules
