feat: replace clipboard copy with config display for SSH sessions

Created ConfigDisplay component that shows full client configuration
in a scrollable modal window, replacing non-functional clipboard copy.

Benefits:
- Works over SSH sessions (no clipboard API needed)
- Shows complete configuration, not just public key
- Scrollable for long configs with keyboard navigation
- Users can select and copy text directly in terminal

Changes:
- Created internal/tui/components/config-display.go
- Updated detail.go to replace copyPublicKey with loadConfig
- Removed clipboard-related fields and message type
- Updated help text: 'c' now shows config
- Key bindings for scrolling: ↑↓, pgup/pgdn, g/G, Esc/q to close

Fixes: wg-admin-qtb

internal/tui/components/config-display.go

@@ -0,0 +1,149 @@
+package components
+
+import (
+	"github.com/charmbracelet/bubbles/viewport"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+)
+
+// ConfigDisplayModel represents a configuration display modal
+type ConfigDisplayModel struct {
+	config    string
+	viewport  viewport.Model
+	Visible   bool
+	Width     int
+	Height    int
+	scrollPos int
+}
+
+// Styles
+var (
+	configModalStyle = lipgloss.NewStyle().
+				Border(lipgloss.RoundedBorder()).
+				BorderForeground(lipgloss.Color("62")).
+				Padding(1, 2).
+				Background(lipgloss.Color("235"))
+	configTitleStyle = lipgloss.NewStyle().
+				Foreground(lipgloss.Color("62")).
+				Bold(true).
+				MarginBottom(1)
+	configHelpStyle = lipgloss.NewStyle().
+			Foreground(lipgloss.Color("241")).
+			MarginTop(1)
+	configContentStyle = lipgloss.NewStyle().
+				Foreground(lipgloss.Color("255")).
+				Width(76)
+)
+
+// NewConfigDisplay creates a new configuration display modal
+func NewConfigDisplay(config string, width, height int) *ConfigDisplayModel {
+	vp := viewport.New(76, 24)
+	vp.SetContent(config)
+
+	return &ConfigDisplayModel{
+		config:    config,
+		viewport:  vp,
+		Visible:   true,
+		Width:     width,
+		Height:    height,
+		scrollPos: 0,
+	}
+}
+
+// Init initializes the configuration display modal
+func (m *ConfigDisplayModel) Init() tea.Cmd {
+	return nil
+}
+
+// Update handles messages for the configuration display modal
+func (m *ConfigDisplayModel) Update(msg tea.Msg) (*ConfigDisplayModel, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "esc", "q":
+			m.Visible = false
+			return m, nil
+		case "up", "k":
+			m.viewport.LineUp(1)
+		case "down", "j":
+			m.viewport.LineDown(1)
+		case "pgup", "b":
+			m.viewport.HalfViewUp()
+		case "pgdown", "f", " ":
+			m.viewport.HalfViewDown()
+		case "g", "home":
+			m.viewport.GotoTop()
+		case "G", "end":
+			m.viewport.GotoBottom()
+		}
+	case tea.WindowSizeMsg:
+		// Update modal dimensions on resize
+		m.Width = msg.Width
+		m.Height = msg.Height
+	}
+
+	var cmd tea.Cmd
+	m.viewport, cmd = m.viewport.Update(msg)
+	return m, cmd
+}
+
+// View renders the configuration display modal
+func (m *ConfigDisplayModel) View() string {
+	if !m.Visible {
+		return ""
+	}
+
+	// Build modal content
+	title := configTitleStyle.Render("📋 Client Configuration")
+	content := m.viewport.View()
+	help := configHelpStyle.Render("↑/j: down • ↓/k: up • pgup/pgdn: page • g/G: top/bottom • Esc: close")
+
+	fullContent := lipgloss.JoinVertical(
+		lipgloss.Left,
+		title,
+		"",
+		content,
+		help,
+	)
+
+	// Apply modal style
+	modal := configModalStyle.Render(fullContent)
+
+	// Center modal on screen
+	modalWidth := lipgloss.Width(modal)
+	modalHeight := lipgloss.Height(modal)
+
+	x := (m.Width - modalWidth) / 2
+	if x < 0 {
+		x = 0
+	}
+	y := (m.Height - modalHeight) / 2
+	if y < 0 {
+		y = 0
+	}
+
+	return lipgloss.Place(m.Width, m.Height,
+		lipgloss.Left, lipgloss.Top,
+		modal,
+		lipgloss.WithWhitespaceChars(" "),
+		lipgloss.WithWhitespaceForeground(lipgloss.Color("235")),
+	)
+}
+
+// IsVisible returns true if the modal is visible
+func (m *ConfigDisplayModel) IsVisible() bool {
+	return m.Visible
+}
+
+// Hide hides the modal
+func (m *ConfigDisplayModel) Hide() {
+	m.Visible = false
+}
+
+// Show shows the modal
+func (m *ConfigDisplayModel) Show(config string) {
+	m.config = config
+	m.viewport.SetContent(config)
+	m.viewport.GotoTop()
+	m.Visible = true
+}