Fix: Ortsnamen-Layer, InfoBox bei Klick, globale Flugabdeckung

Ortsnamen: Esri World Boundaries als zuschaltbarer Imagery-Layer.
InfoBox: CSS-Ausblendung entfernt, Dark-Theme Styling.
Flugverkehr: Batch-Groesse 3, Pause 3s, zufaellige Reihenfolge —
alle Regionen bekommen Daten statt nur Europa.

static/js/app.js

@@ -5,6 +5,7 @@ const Globe = {
     viewer: null,
     layers: {},
     _statsInterval: null,
+    _labelsLayer: null,
 
     init() {
         // Cesium Ion Token
@@ -82,6 +83,22 @@ const Globe = {
         document.getElementById('bottom-stats').textContent = 'Globe initialisiert — Lade Daten...';
     },
 
+    _toggleLabels(on) {
+        if (on && !this._labelsLayer) {
+            this._labelsLayer = this.viewer.imageryLayers.addImageryProvider(
+                new Cesium.UrlTemplateImageryProvider({
+                    url: 'https://server.arcgisonline.com/ArcGIS/rest/services/Reference/World_Boundaries_and_Places/MapServer/tile/{z}/{y}/{x}',
+                    maximumLevel: 18,
+                    credit: 'Esri',
+                })
+            );
+            this._labelsLayer.alpha = 0.9;
+        } else if (!on && this._labelsLayer) {
+            this.viewer.imageryLayers.remove(this._labelsLayer);
+            this._labelsLayer = null;
+        }
+    },
+
     _setupLayerToggles() {
         var toggles = {
             'layer-flights': function(on) { on ? FlightsLayer.start(Globe.viewer) : FlightsLayer.stop(); },
@@ -89,7 +106,7 @@ const Globe = {
             'layer-quakes': function(on) { on ? QuakesLayer.start(Globe.viewer) : QuakesLayer.stop(); },
             'layer-gdelt': function(on) { on ? GdeltLayer.start(Globe.viewer) : GdeltLayer.stop(); },
             'layer-daynight': function(on) { Globe.viewer.scene.globe.enableLighting = on; },
-            'layer-labels': function(on) { /* Phase 2 */ },
+            'layer-labels': function(on) { Globe._toggleLabels(on); },
         };
         Object.keys(toggles).forEach(function(id) {
             var cb = document.getElementById(id);