Add a Debian package and bash completion

make deb builds dist/jarl_<version>_<arch>.deb with dpkg-deb alone (no
root), for the host or another architecture (DEB_ARCH=arm64). The package
creates the jarl user and directories and an example jarl.yaml on the
first install, restarts a running jarld on upgrades, never touches
/etc/jarl/jarl.yaml, stops jarld on removal, and keeps Jarl's data even
on purge.

make install and the package install bash completion for jarl and jarld.
Besides commands and flags it completes server and group names from the
CLI configuration, zone, view, ACL, TSIG key and user names from the
server, and record types. make dist includes the completion scripts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

deploy/debian/prerm

@@ -0,0 +1,12 @@
+#!/bin/sh
+# Jarl: runs before the package's files are removed (also on upgrades).
+set -e
+
+# On removal (not on upgrade) stop jarld and remove its boot-time link.
+# named keeps running with the configuration Jarl last wrote.
+if [ "$1" = remove ] && [ -d /run/systemd/system ]; then
+	systemctl stop jarl.service 2>/dev/null || true
+	systemctl disable jarl.service 2>/dev/null || true
+fi
+
+exit 0