Switch greeter from tuigreet to regreet

- Replace greetd-tuigreet with greetd-regreet + cage in packages.txt
- Add greetd/config.toml and greetd/regreet.toml (Materia-dark theme)
- Update install.sh to deploy greetd configs to /etc/greetd/
- Fix powermenu.sh awk parsing (use $NF instead of $2 for icon glyphs)

install.sh

@@ -34,4 +34,8 @@ ln -sf "$(pwd)/scripts/clipboard.sh" ~/.local/bin/clipboard-picker
 echo "==> Enabling systemd user services"
 mkdir -p ~/.config/systemd/user
 
+echo "==> Deploying greetd config"
+sudo cp "$(pwd)/greetd/config.toml" /etc/greetd/config.toml
+sudo cp "$(pwd)/greetd/regreet.toml" /etc/greetd/regreet.toml
+
 echo "==> Done. Start Niri with: niri-session"