setup: check network connectivity before installer and launch nmtui if offline

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

setup/tui-install.sh

@@ -143,6 +143,19 @@ command -v pacman &>/dev/null || die "pacman not found — Arch Linux required."
 
 require_dialog
 
+if ! ping -c1 -W3 archlinux.org &>/dev/null; then
+    dialog --backtitle "$BACKTITLE" \
+           --title " No Network Detected " \
+           --msgbox "\n  No internet connection found.\n\n  nmtui will open so you can configure networking.\n  Close nmtui when done to continue the installer.\n" 11 58
+    nmtui
+    if ! ping -c1 -W3 archlinux.org &>/dev/null; then
+        dialog --backtitle "$BACKTITLE" \
+               --title " Still Offline " \
+               --yesno "\n  Still no internet connection.\n\n  Packages cannot be downloaded without network access.\n\n  Continue anyway?" 11 58 \
+            || { clear; echo "Aborted — no network."; exit 1; }
+    fi
+fi
+
 > "$LOG"
 printf "Dotfiles install: %s\nDotfiles dir:    %s\n" "$(date)" "$DOTFILES_DIR" >> "$LOG"