Keep MealQuest firewall rules first and off docker.service

Address review of the port 8090 firewall:

- Insert the three MealQuest rules at the top of DOCKER-USER, ahead of
  other projects' rules. Each run deletes every rule tagged
  "mealquest-firewall" and re-inserts them at positions 1-3, so re-runs
  restore the order and never duplicate.
- Scope the match to MealQuest's published address with
  --ctorigdst 10.60.1.14, so outbound container connections to a remote
  :8090 are not matched.
- Drop the docker.service ExecStartPost drop-in, which made a firewall
  error fatal to the shared Docker daemon. The unit is now PartOf= and
  WantedBy= docker.service: it re-runs on every Docker start or restart
  and fails visibly on its own without failing docker.service.

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

deploy/systemd/mealquest-firewall.service

@@ -0,0 +1,22 @@
+# Applies the MealQuest DOCKER-USER rules (/usr/local/sbin/mealquest-firewall).
+#
+# PartOf= re-runs this unit whenever docker.service is stopped or restarted,
+# and WantedBy=docker.service starts it whenever docker.service starts. Both
+# are one-way: a failure here fails this unit visibly and never fails
+# docker.service.
+#
+# Start MealQuest only after this unit has succeeded:
+#   systemctl start mealquest-firewall && docker compose up -d
+[Unit]
+Description=Restrict MealQuest port 8090 to Traefik (DOCKER-USER)
+After=docker.service
+Requires=docker.service
+PartOf=docker.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/usr/local/sbin/mealquest-firewall
+
+[Install]
+WantedBy=multi-user.target docker.service

deploy/systemd/mealquest-firewall.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+# Restrict the MealQuest published host port (10.60.1.14:8090) to Traefik
+# (10.60.1.33) and the Docker host itself (10.60.1.14); drop every other
+# source.
+#
+# DOCKER-USER runs after Docker's DNAT, so the destination there is the
+# container address and port, not the published ones. Match the original
+# destination address and port with conntrack instead of -d/--dport.
+#
+# The rules must sit at the top of DOCKER-USER, ahead of any other project's
+# rules (an earlier RETURN or DROP would decide MealQuest traffic first).
+# Every run deletes all rules tagged with the mealquest-firewall comment and
+# re-inserts them at positions 1-3, so re-runs leave the same ordered rules
+# and no duplicates. Installed as /usr/local/sbin/mealquest-firewall.
+set -eu
+
+tag="-m comment --comment mealquest-firewall"
+match="-m conntrack --ctorigdst 10.60.1.14 --ctorigdstport 8090 --ctdir ORIGINAL"
+
+rules=$(iptables -w -S DOCKER-USER)
+printf '%s\n' "$rules" | while read -r _ chain spec; do
+	case " $spec " in
+	*" --comment mealquest-firewall "*) iptables -w -D "$chain" $spec ;;
+	esac
+done
+
+iptables -w -I DOCKER-USER 1 -s 10.60.1.33/32 $match $tag -j RETURN
+iptables -w -I DOCKER-USER 2 -s 10.60.1.14/32 $match $tag -j RETURN
+iptables -w -I DOCKER-USER 3 $match $tag -j DROP