bd-154: Implement bd daemons stop and restart subcommands

internal/daemon/kill_unix.go

@@ -0,0 +1,15 @@
+//go:build unix
+
+package daemon
+
+import (
+	"fmt"
+	"syscall"
+)
+
+func killProcess(pid int) error {
+	if err := syscall.Kill(pid, syscall.SIGTERM); err != nil {
+		return fmt.Errorf("failed to send SIGTERM to PID %d: %w", pid, err)
+	}
+	return nil
+}