dnsmasq: add foreground CMD to the image

The image had no command, so the container exited immediately (0).
dnsmasq also daemonizes by default; -k keeps it as PID 1.

dankclaw/dnsmasq/Containerfile

@@ -2,3 +2,5 @@
 # Build on dankclaw:  podman build -t localhost/dnsmasq:latest -f Containerfile .
 FROM alpine:3.20
 RUN apk add --no-cache dnsmasq
+# -k keeps dnsmasq in the foreground (PID 1) so the container stays up.
+CMD ["/usr/sbin/dnsmasq", "-k", "-C", "/etc/dnsmasq.conf"]