Add smart user detection and selection for kiosk client install

Added intelligent user selection that scans /home directory and
presents available users, making it much easier to install the
kiosk client for the correct user account.

Features:
1. Smart User Detection
   - Scans /etc/passwd for real users (UID >= 1000)
   - Excludes system accounts (nologin, /bin/false)
   - Shows username, UID, and home directory
   - Presents numbered list of available users

2. Intelligent Defaults
   - Auto-suggests SUDO_USER if available
   - Falls back to first detected user
   - Highlights suggested choice as default

3. Manual Override
   - Option to manually enter username
   - Validates entered username exists
   - Shows confirmation with UID

4. Improved User Experience
   - install_client_only(): Uses new select_user function
   - configure_local_client(): Shows current user, offers to change
   - Clear feedback on user selection
   - Proper error handling for invalid selections

5. Verified Ownership
   All user configs are properly owned by selected user:
   - ~/.baresip/config (chown in configure_baresip:1879)
   - ~/.baresip/accounts (chown in configure_baresip:1879)
   - ~/.config/systemd/user/* (chown in enable_client_services:1962)
   - ~/.config/wireplumber/* (chown in configure_audio_ducking:1067)
   - All PipeWire/audio operations run as selected user

Example Flow:
  $ sudo ./easy-asterisk-interactive-v1.28.sh
  > Install Client Only

  Scanning for users...

    1) kiosk (UID: 1000, Home: /home/kiosk)
    2) admin (UID: 1001, Home: /home/admin)
    3) Enter username manually

  Select user [1]: 1
  ✓ Selected user: kiosk (UID: 1000)

This makes it much easier to install on kiosk systems where you
might not remember the exact username, and ensures all configs
are created with proper ownership from the start.

easy-asterisk-interactive-v1.28.sh

@@ -67,6 +67,80 @@ generate_password() {
     tr -dc 'A-Za-z0-9' < /dev/urandom | head -c 16
 }
 
+select_user() {
+    # Scan /home for real users (exclude system accounts)
+    local -a users=()
+    local -a user_ids=()
+    local count=0
+
+    echo "Scanning for users..."
+    echo ""
+
+    # Get users from /home with valid shells
+    while IFS=: read -r username _ uid _ _ homedir shell; do
+        # Only include users with UID >= 1000 and valid shell
+        if [[ $uid -ge 1000 && -d "$homedir" && "$shell" != "/usr/sbin/nologin" && "$shell" != "/bin/false" ]]; then
+            ((count++))
+            users+=("$username")
+            user_ids+=("$uid")
+            echo "  ${count}) ${username} (UID: ${uid}, Home: ${homedir})"
+        fi
+    done < /etc/passwd
+
+    # Add option to manually enter username
+    ((count++))
+    echo "  ${count}) Enter username manually"
+    echo ""
+
+    # Suggest default based on SUDO_USER or first user found
+    local default_choice=""
+    local default_user="${SUDO_USER:-}"
+    if [[ -z "$default_user" ]]; then
+        default_user="${users[0]:-}"
+        default_choice="1"
+    else
+        # Find index of SUDO_USER
+        for i in "${!users[@]}"; do
+            if [[ "${users[$i]}" == "$default_user" ]]; then
+                default_choice=$((i + 1))
+                break
+            fi
+        done
+    fi
+
+    if [[ -n "$default_choice" ]]; then
+        read -p "Select user [${default_choice}]: " choice
+        choice="${choice:-$default_choice}"
+    else
+        read -p "Select user: " choice
+    fi
+
+    # Validate choice
+    if [[ "$choice" =~ ^[0-9]+$ && "$choice" -le "${#users[@]}" && "$choice" -gt 0 ]]; then
+        local idx=$((choice - 1))
+        KIOSK_USER="${users[$idx]}"
+        KIOSK_UID="${user_ids[$idx]}"
+        echo ""
+        print_success "Selected user: $KIOSK_USER (UID: $KIOSK_UID)"
+        return 0
+    elif [[ "$choice" == "$count" ]]; then
+        # Manual entry
+        echo ""
+        read -p "Enter username: " KIOSK_USER
+        if id "$KIOSK_USER" >/dev/null 2>&1; then
+            KIOSK_UID=$(id -u "$KIOSK_USER")
+            print_success "Selected user: $KIOSK_USER (UID: $KIOSK_UID)"
+            return 0
+        else
+            print_error "User '$KIOSK_USER' not found"
+            return 1
+        fi
+    else
+        print_error "Invalid selection"
+        return 1
+    fi
+}
+
 load_config() {
     if [[ -f "$CONFIG_FILE" ]]; then
         source "$CONFIG_FILE" 2>/dev/null || true
@@ -1192,13 +1266,33 @@ router_doctor() {
 configure_local_client() {
     print_header "Configure Local Client"
     load_config
+
+    # If KIOSK_USER already set from config, show and ask if want to change
+    if [[ -n "$KIOSK_USER" ]]; then
+        echo "Current configured user: $KIOSK_USER"
+        read -p "Change user? [y/N]: " change_user
+        if [[ "$change_user" =~ ^[Yy]$ ]]; then
+            KIOSK_USER=""
+            KIOSK_UID=""
+        fi
+    fi
+
+    # If still no user, select one
     if [[ -z "$KIOSK_USER" ]]; then
-        local default_user="${SUDO_USER:-$USER}"
-        read -p "User [$default_user]: " KIOSK_USER
-        KIOSK_USER="${KIOSK_USER:-$default_user}"
+        echo ""
+        echo "Select the user to configure:"
+        echo ""
+        if ! select_user; then
+            print_error "User selection failed"
+            return 1
+        fi
+    else
+        # Ensure KIOSK_UID is set
         KIOSK_UID=$(id -u "$KIOSK_USER" 2>/dev/null)
     fi
 
+    echo ""
+
     if [[ ! -d "/home/${KIOSK_USER}/.baresip" ]]; then
         print_error "Baresip not installed for $KIOSK_USER"
         echo ""
@@ -2165,11 +2259,15 @@ install_server_only() {
 
 install_client_only() {
     print_header "Client Installation"
-    local default_user="${SUDO_USER:-$USER}"
-    read -p "User [$default_user]: " target_user
-    KIOSK_USER="${target_user:-$default_user}"
-    KIOSK_UID=$(id -u "$KIOSK_USER")
+    echo "Select the user to install the kiosk client for:"
+    echo ""
 
+    if ! select_user; then
+        print_error "User selection failed"
+        return 1
+    fi
+
+    echo ""
     read -p "Server (IP or domain): " ASTERISK_HOST
     read -p "SIP Password: " SIP_PASSWORD