refactor: consolidate service commands into modular structure with complete logic

Replace individual service command initialization with unified InitServiceCmd()
that creates a complete service command hierarchy. Port all original logic
from initStartCmd, initStopCmd, initRestartCmd, initReloadCmd, initStatusCmd,
and initUninstallCmd into ServiceCommand methods with proper dependency injection.

Key changes:
- Port complete Start logic including config validation, service installation,
  DNS management, and self-check functionality
- Port complete Stop logic with deactivation pin validation and DNS cleanup
- Port complete Restart logic with config validation and DNS restoration
- Port complete Reload logic with HTTP status handling and restart fallback
- Port complete Status logic with proper exit codes
- Port complete Uninstall logic with cleanup file removal
- Add all necessary flags to service commands (iface, pin, etc.)
- Use InitInterfacesCmd() for interfaces subcommand
- Simplify cli.go by replacing multiple init calls with single InitServiceCmd()

This refactoring eliminates code duplication, improves maintainability, and
ensures all service commands have their complete original functionality.

cmd/cli/commands_interfaces.go

@@ -82,7 +82,6 @@ func InitInterfacesCmd() *cobra.Command {
 		},
 	}
 	interfacesCmd.AddCommand(listInterfacesCmd)
-	rootCmd.AddCommand(interfacesCmd)
 
 	return interfacesCmd
 }