feat: NASA Earthdata/GIBS Integration - Imagery-Switcher + FIRMS Layer

- imagery.js: WMTS-Support fuer NASA GIBS + 4 neue Quellen (MODIS Terra, VIIRS SNPP, GOES East/West)
- firms.js: Neuer VIIRS Thermal Anomalies Layer (375m, tagesaktuell, Braende/Industriewaerme)
- nightlights.js: NRT-Upgrade (dynamisches Datum statt hardcodiert 2024-01-01)
- index.html: Optgroups im Imagery-Select, FIRMS-Checkbox, Script-Tag
- app.js: FIRMS Toggle
- globe.css: dot-firms Farbe

Alle NASA-Daten kostenlos via GIBS WMTS, kein API-Key noetig.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

static/js/layers/firms.js

@@ -0,0 +1,38 @@
+/**
+ * FIRMS Layer: NASA VIIRS Thermal Anomalies (375m).
+ * Zeigt aktive Braende, Industriewaerme und Vulkanaktivitaet als Overlay.
+ * Datenquelle: NASA GIBS WMTS (kostenlos, kein API-Key).
+ */
+const FirmsLayer = {
+    _viewer: null,
+    _layer: null,
+
+    start(viewer) {
+        if (this._layer) return;
+        this._viewer = viewer;
+        var today = new Date().toISOString().slice(0, 10);
+        this._layer = viewer.imageryLayers.addImageryProvider(
+            new Cesium.WebMapTileServiceImageryProvider({
+                url: "https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/wmts.cgi",
+                layer: "VIIRS_SNPP_Thermal_Anomalies_375m_All",
+                tileMatrixSetID: "250m",
+                format: "image/png",
+                style: "default",
+                time: today,
+                tileWidth: 512,
+                tileHeight: 512,
+                tilingScheme: new Cesium.GeographicTilingScheme(),
+                tileMatrixLabels: ["0","1","2","3","4","5","6","7","8"],
+                credit: "NASA VIIRS Thermal Anomalies",
+            })
+        );
+        this._layer.alpha = 0.9;
+    },
+
+    stop() {
+        if (this._layer && this._viewer) {
+            this._viewer.imageryLayers.remove(this._layer);
+            this._layer = null;
+        }
+    },
+};