Fix Debian package build issues

- Remove debian/compat file (conflicts with Build-Depends)
- Fix debian/install to use correct readme.md filename
- Update verify-deb.sh to mark debian/compat as optional
- Add -Zgzip flag to dpkg-buildpackage for compatibility
  (uses gzip instead of zstd for better compatibility)
- Update verify-deb.sh to check optional vs required files

Package now builds and installs successfully on systems
without zstd support.

debian/sensorpajen.postrm.debhelper

@@ -0,0 +1,12 @@
+# Automatically added by dh_installsystemd/13.14.1ubuntu5
+if [ "$1" = remove ] && [ -d /run/systemd/system ] ; then
+	systemctl --system daemon-reload >/dev/null || true
+fi
+# End automatically added section
+# Automatically added by dh_installsystemd/13.14.1ubuntu5
+if [ "$1" = "purge" ]; then
+	if [ -x "/usr/bin/deb-systemd-helper" ]; then
+		deb-systemd-helper purge 'sensorpajen.service' >/dev/null || true
+	fi
+fi
+# End automatically added section