feat(tui): fullscreen detail view + enriched sidebar content

On narrow terminals (<120 cols), Enter opens a fullscreen detail view
instead of the sidebar that can't be seen. Wide terminals keep existing
sidebar toggle behavior.

Enrich detail panel with: state since, last success, connection chain
diagnostic, probe results, latency histogram, extended endpoint fields
(interval/timeout/method/codes/regions/description), push token,
maintenance window name. Breadcrumb shown in fullscreen mode only.

internal/tui/view_dashboard.go

@@ -92,6 +92,8 @@ func (m Model) View() string {
 		return ""
 	case stateLogs:
 		return m.viewLogsFullscreen()
+	case stateDetailFullscreen:
+		return m.viewDetailFullscreen()
 	case stateAlertDetail:
 		return m.viewAlertDetailPanel()
 	case stateSettings: