fix: add blank row between Devices and meshd sections on dashboard

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: gitcoder89431

internal/screens/dashboard.go

@@ -173,6 +173,7 @@ func (d Dashboard) devicesSection(width int) string {
 	if d.localDevice.ID == "" && len(d.devices) == 0 {
 		rows = append(rows, d.theme.Muted.Render("No devices — add one via Connect"))
 	}
+	rows = append(rows, "")
 	return strings.Join(rows, "\n")
 }