Add Panama system health diagnostics

tests/quickshell/fixtures/doctor/bin/systemctl

@@ -0,0 +1,9 @@
+#!/usr/bin/bash
+
+set -euo pipefail
+
+service="${4:-}"
+case ",${PANAMA_DOCTOR_FIXTURE_STOPPED:-}," in
+    *",$service,"*) exit 3 ;;
+esac
+printf 'fixture-secret-token\n'