Add WireGuard TUI implementation

- Add Go TUI with bubbletea for WireGuard management
- Implement client CRUD operations with QR code generation
- Add configuration and validation modules
- Install/update scripts for client setup
- Update Makefile to build binaries to bin/ directory
- Add .gitignore for Go projects

internal/tui/screens/add.go

@@ -0,0 +1,152 @@
+package screens
+
+import (
+	"fmt"
+
+	"github.com/calmcacil/wg-admin/internal/config"
+	"github.com/calmcacil/wg-admin/internal/validation"
+	"github.com/calmcacil/wg-admin/internal/wireguard"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/huh"
+	"github.com/charmbracelet/lipgloss"
+)
+
+// AddScreen is a form for adding new WireGuard clients
+type AddScreen struct {
+	form     *huh.Form
+	quitting bool
+}
+
+// Styles
+var (
+	addTitleStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("62")).
+			Bold(true).
+			MarginBottom(1)
+	addHelpStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("241")).
+			MarginTop(1)
+)
+
+// NewAddScreen creates a new add screen
+func NewAddScreen() *AddScreen {
+	// Get default DNS from config
+	cfg, err := config.LoadConfig()
+	defaultDNS := "8.8.8.8, 8.8.4.4"
+	if err == nil && cfg.DNSServers != "" {
+		defaultDNS = cfg.DNSServers
+	}
+
+	// Create the form
+	form := huh.NewForm(
+		huh.NewGroup(
+			huh.NewInput().
+				Key("name").
+				Title("Client Name").
+				Description("Name for the new client (alphanumeric, -, _)").
+				Placeholder("e.g., laptop-john").
+				Validate(func(s string) error {
+					return validation.ValidateClientName(s)
+				}),
+
+			huh.NewInput().
+				Key("dns").
+				Title("DNS Servers").
+				Description("Comma-separated IPv4 addresses").
+				Placeholder("e.g., 8.8.8.8, 8.8.4.4").
+				Value(&defaultDNS).
+				Validate(func(s string) error {
+					return validation.ValidateDNSServers(s)
+				}),
+
+			huh.NewConfirm().
+				Key("use_psk").
+				Title("Use Preshared Key").
+				Description("Enable additional security layer with a preshared key").
+				Affirmative("Yes").
+				Negative("No"),
+		),
+	)
+
+	return &AddScreen{
+		form:     form,
+		quitting: false,
+	}
+}
+
+// Init initializes the add screen
+func (s *AddScreen) Init() tea.Cmd {
+	return s.form.Init()
+}
+
+// Update handles messages for the add screen
+func (s *AddScreen) Update(msg tea.Msg) (Screen, tea.Cmd) {
+	var cmds []tea.Cmd
+
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "q", "ctrl+c", "esc":
+			// Cancel and return to list
+			return nil, nil
+		}
+	}
+
+	// Update the form
+	form, cmd := s.form.Update(msg)
+	if f, ok := form.(*huh.Form); ok {
+		s.form = f
+	}
+	cmds = append(cmds, cmd)
+
+	// Check if form is completed
+	if s.form.State == huh.StateCompleted {
+		name := s.form.GetString("name")
+		dns := s.form.GetString("dns")
+		usePSK := s.form.GetBool("use_psk")
+
+		// Create the client
+		return s, s.createClient(name, dns, usePSK)
+	}
+
+	return s, tea.Batch(cmds...)
+}
+
+// View renders the add screen
+func (s *AddScreen) View() string {
+	if s.quitting {
+		return ""
+	}
+
+	content := lipgloss.JoinVertical(
+		lipgloss.Left,
+		addTitleStyle.Render("Add New WireGuard Client"),
+		s.form.View(),
+		addHelpStyle.Render("Press Enter to submit • Esc to cancel"),
+	)
+
+	return content
+}
+
+// createClient creates a new WireGuard client
+func (s *AddScreen) createClient(name, dns string, usePSK bool) tea.Cmd {
+	return func() tea.Msg {
+		// Create the client via wireguard package
+		err := wireguard.CreateClient(name, dns, usePSK)
+		if err != nil {
+			return errMsg{err: fmt.Errorf("failed to create client: %w", err)}
+		}
+
+		// Return success message
+		return ClientCreatedMsg{
+			Name: name,
+		}
+	}
+}
+
+// Messages
+
+// ClientCreatedMsg is sent when a client is successfully created
+type ClientCreatedMsg struct {
+	Name string
+}