fix: the web service starts once libpq can be found.

debian-package/debian/postinst

@@ -70,6 +70,12 @@ case "$1" in
         # The firewall is not touched here. Enabling it, allowing SSH and
         # setting the forward policy all belong to vpn-router-setup, which does
         # them only once the configuration says this host is a router.
+
+        # The web service waits for libpq in the linker cache, which dpkg
+        # refreshes after this script, so it is started without waiting for it.
+        if [ -d /run/systemd/system ]; then
+            systemctl --no-block restart vpn-router-web.service >/dev/null 2>&1 || true
+        fi
         ;;
 esac