Revert "Drop unrelated privileged heredoc scanner"

This reverts commit 4c23077f80.

test/shell.d/fixtures/privileged-heredoc/shadowed-assignment-home-path.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+# The name is introduced with a packaged root-owned value and then reassigned to
+# one under the user's home. Judging the first assignment would read this as the
+# path it no longer holds.
+target=/usr/share/omarchy/bin/agent
+target="$HOME/.local/share/omarchy/bin/agent"
+
+# omarchy:heredoc-expands paths=none -- target is the packaged agent path under /usr
+cat <<EOF | sudo tee /etc/systemd/system/omarchy-agent.service >/dev/null
+[Service]
+ExecStart=$target
+EOF