Refactor user input prompts in scripts to use whiptail for better UX

- Replaced standard input prompts with whiptail dialogs in 03_generate_secrets.sh and 05_configure_services.sh for domain, email, OpenAI API key, and n8n worker count.
- Added validation messages using whiptail for empty inputs and invalid formats.
- Introduced new utility functions in utils.sh for whiptail integration, ensuring the script checks for whiptail availability.

scripts/utils.sh

@@ -49,3 +49,64 @@ log_info() {
     local combined_message="[INFO] ${timestamp}: ${message}"
     log_message "${combined_message}"
 }
+
+# --- Whiptail helpers ---
+# Ensure whiptail is available
+require_whiptail() {
+    if ! command -v whiptail >/dev/null 2>&1; then
+        log_error "'whiptail' is not installed. Install with: sudo apt-get install -y whiptail"
+        exit 1
+    fi
+}
+
+# Input box. Usage: wt_input "Title" "Prompt" "default"
+# Echoes the input on success; returns 0 on OK, 1 on Cancel
+wt_input() {
+    local title="$1"
+    local prompt="$2"
+    local default_value="$3"
+    local result
+    result=$(whiptail --title "$title" --inputbox "$prompt" 15 80 "$default_value" 3>&1 1>&2 2>&3)
+    local status=$?
+    if [ $status -ne 0 ]; then
+        return 1
+    fi
+    echo "$result"
+    return 0
+}
+
+# Password box. Usage: wt_password "Title" "Prompt"
+# Echoes the input on success; returns 0 on OK, 1 on Cancel
+wt_password() {
+    local title="$1"
+    local prompt="$2"
+    local result
+    result=$(whiptail --title "$title" --passwordbox "$prompt" 15 80 3>&1 1>&2 2>&3)
+    local status=$?
+    if [ $status -ne 0 ]; then
+        return 1
+    fi
+    echo "$result"
+    return 0
+}
+
+# Yes/No box. Usage: wt_yesno "Title" "Prompt" "default"  (default: yes|no)
+# Returns 0 for Yes, 1 for No/Cancel
+wt_yesno() {
+    local title="$1"
+    local prompt="$2"
+    local default_choice="$3"
+    if [ "$default_choice" = "yes" ]; then
+        whiptail --title "$title" --yesno "$prompt" 10 80
+    else
+        whiptail --title "$title" --defaultno --yesno "$prompt" 10 80
+    fi
+}
+
+# Message box. Usage: wt_msg "Title" "Message"
+wt_msg() {
+    local title="$1"
+    local message="$2"
+    whiptail --title "$title" --msgbox "$message" 10 80
+}
+