Fail the suite on privileged writes through unquoted heredocs

An installer that writes a root-owned file through a heredoc with an
unquoted delimiter (<<EOF rather than <<'EOF') has the installing user's
shell expand the body first, so a user-controlled value is baked in as a
literal. Send that into /etc and root later reads or executes a path the
unprivileged user picked: a udev rule carrying
$HOME/.local/share/omarchy/bin/... resolves through a symlink that user
owns, so replacing the symlink gets their code run as root.

Add the static check. A heredoc is flagged when its delimiter is
unquoted, its body contains an install-time expansion (escaped \$VAR does
not count, since that is left for a root daemon to expand at runtime),
and its output reaches /etc, /usr, /opt, /srv, /boot or /var/lib via sudo
tee, sudo dd, a redirect, or an install/cp/mv of the generated scratch
file. Destinations written as variables are resolved from the file's own
assignments.

Sites that genuinely need install-time expansion declare it inline:

  # omarchy:heredoc-expands paths=none -- $servers is a validated IP list

paths= is machine-checked against the expansions the scanner finds to be
path-shaped, so this cannot become a rubber stamp: adding a $HOME/... to
an already-annotated heredoc makes the declaration false and trips the
check again. Path expansions anchored under a root-owned prefix, as in
"/etc/systemd/system/$unit", are correctly not path-shaped.

Annotate the sites the scan reports, each of which expands a scalar: DNS
addresses in omarchy-dns, a literal PAM line in
omarchy-setup-security-fingerprint, kernel cmdline parameters and
usernames in omarchy-upgrade-to-quattro. omarchy-provision-owner expanded
a unit name that was already a constant, so its delimiter is now quoted
and the name hardcoded; the generated unit file is byte-identical.
omarchy-windows-vm declares paths=storage,shared, the only site that
interpolates a user-chosen path.

Fixtures prove non-vacuity in both directions: the write routes other
than a pipe into sudo tee, the shapes that must stay quiet, udev rules
and a shutdown unit taken verbatim from this repository's history, and
the rubber-stamp case where a paths=none annotation on a baked $HOME path
still fails.

bin/omarchy-upgrade-to-quattro

@@ -597,6 +597,9 @@ preserve_kernel_cmdline_root() {
   fi
 
   log "Preserving the kernel cmdline root parameters in $default_conf"
+  # omarchy:heredoc-expands paths=none -- ${boot_params[*]} is the kernel
+  # cmdline fragment assembled above from findmnt output (root=, rootflags=),
+  # not a filesystem path this script controls.
   as_root tee -a "$default_conf" >/dev/null <<EOF
 # Written by omarchy-upgrade-to-quattro. The += drop-ins in
 # /etc/limine-entry-tool.d/ stop limine-entry-tool from reading
@@ -1395,6 +1398,9 @@ EOF
       autologin_user=$(as_root awk -F= '/^User=/ { print $2; exit }' /etc/sddm.conf.d/autologin.conf 2>/dev/null || true)
     fi
     [[ -n ${autologin_user:-} ]] || autologin_user="$target_user"
+    # omarchy:heredoc-expands paths=none -- $autologin_user is a username, read
+    # back from the root-owned drop-in or falling back to $target_user. Same
+    # mechanism as the old getty override: a name expands, no path does.
     cat <<EOF | as_root tee /etc/sddm.conf.d/autologin.conf >/dev/null
 [Autologin]
 User=$autologin_user
@@ -1405,6 +1411,8 @@ EOF
   fi
 
   as_root install -d -m 0755 -o sddm -g sddm /var/lib/sddm 2>/dev/null || as_root install -d -m 0755 /var/lib/sddm
+  # omarchy:heredoc-expands paths=none -- $target_user is a username, not a
+  # path; SDDM's state file records who logged in last.
   cat <<EOF | as_root tee /var/lib/sddm/state.conf >/dev/null
 [Last]
 Session=omarchy.desktop