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/app.js

@@ -176,6 +176,7 @@ const Globe = {
             'layer-iss': function(on) { on ? ISSLayer.start(Globe.viewer) : ISSLayer.stop(); },
             'layer-disasters': function(on) { on ? DisastersLayer.start(Globe.viewer) : DisastersLayer.stop(); },
             'layer-weather': function(on) { on ? WeatherLayer.start(Globe.viewer) : WeatherLayer.stop(); },
+            'layer-firms': function(on) { on ? FirmsLayer.start(Globe.viewer) : FirmsLayer.stop(); },
             'layer-daynight': function(on) { Globe.viewer.scene.globe.enableLighting = on; },
             'layer-terminator': function(on) { on ? TerminatorLayer.start(Globe.viewer) : TerminatorLayer.stop(); },
             'layer-timezones': function(on) { on ? TimezonesLayer.start(Globe.viewer) : TimezonesLayer.stop(); },