refactor setup script to improve argument handling for continuation flag

setup.sh

@@ -455,6 +455,7 @@ main() {
         git clone "$GIT_REPO" "$DOTFILES_DIR" || die "Failed to clone dotfiles repository"
     fi
     
+    if [ -n "${1:-}" ]; then
         CONTINUE=$1
         if [ "$CONTINUE" = "--continue" ]; then
             log_info "Continuing setup..."
@@ -464,6 +465,13 @@ main() {
             check_selinux
             install_nix
         fi
+    else
+        warning_prompt
+        prepare_hostname
+        check_selinux
+        install_nix
+    fi
+
 
     install_home_manager
     setup_symlinks