fix: remove chatty install message from postinstall script

README already documents the setup steps. Package install scripts
should be silent on success.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dist/postinstall.sh

@@ -26,14 +26,3 @@ if command -v systemctl >/dev/null 2>&1; then
     fi
 fi
 
-# Only show the setup message on first install (not upgrades).
-action="${1:-}"
-case "$action" in
-    # Debian first install or RPM first install ($1=1).
-    configure|1)
-        if ! systemctl is-enabled --quiet favoritter 2>/dev/null; then
-            echo "Favoritter installed. Configure /etc/favoritter/favoritter.env then run:"
-            echo "  sudo systemctl enable --now favoritter"
-        fi
-        ;;
-esac