fix: add background dimming to config display modal

Config display modal now dims background content before showing,
following the same pattern as delete confirmation modal.
This provides visual consistency across all modals and makes
it clear to users when a modal is active.

Fixes: wg-admin-bfe

internal/tui/screens/detail.go

@@ -137,7 +137,18 @@ func (s *DetailScreen) Update(msg tea.Msg) (Screen, tea.Cmd) {
 func (s *DetailScreen) View() string {
 	// Handle config display modal
 	if s.showConfig && s.configDisplay != nil {
-		return s.configDisplay.View()
+		// Render underlying content dimmed
+		content := s.renderContent()
+		dimmedContent := lipgloss.NewStyle().
+			Foreground(lipgloss.Color("244")).
+			Render(content)
+
+		// Overlay config display modal
+		return lipgloss.JoinVertical(
+			lipgloss.Left,
+			dimmedContent,
+			s.configDisplay.View(),
+		)
 	}
 
 	// Handle confirmation modal