- firewallUtilities: add closeConnectionsFromIP() using conntrack -D -s IP
- addBannedIP: when IP already banned, close connections and return success message
- Frontend: always call API on Ban IP so backend can close connections; show server message
- Install: add conntrack-tools (RHEL) / conntrack (Debian/Ubuntu) to all install paths
(rhel_deps, debian_deps, install_modules/01_verify_deps, install.py, venvsetup)