Revert "Drop unrelated privileged heredoc scanner"

This reverts commit 4c23077f80.

test/shell.d/fixtures/privileged-heredoc/nested-parameter-default.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# omarchy:heredoc-expands paths=none -- review regression fixture
+sudo tee /etc/omarchy/review.conf >/dev/null <<EOF
+ExecStart=${target:-$HOME/.local/bin/payload}
+EOF