scripts: also wire fingerprint into greetd login

Adds /etc/pam.d/greetd to the TARGETS array so re-running
enable-fingerprint.sh extends fprintd auth to the regreet login
screen. Cold-boot timing and silent-touch UX caveats documented
in the spec are accepted as-is — fingerprint failure falls back to
password, no risk of lockout.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/enable-fingerprint.sh

@@ -17,7 +17,7 @@ if ! command -v fprintd-enroll >/dev/null 2>&1; then
 fi
 
 PAM_LINE="auth      sufficient    pam_fprintd.so"
-TARGETS=(/etc/pam.d/sudo /etc/pam.d/hyprlock)
+TARGETS=(/etc/pam.d/sudo /etc/pam.d/hyprlock /etc/pam.d/greetd)
 
 for f in "${TARGETS[@]}"; do
     if [ ! -f "$f" ]; then