atmosphere: add stable air haze behind terrain

config.js

@@ -333,6 +333,14 @@ window.CONFIG = {
             maxAlpha: 0.65,
             color: [0.58, 0.64, 0.72]
         },
+        airHaze: {
+            enabled: true,
+            scaleHeightKm: 8.5,
+            density: 0.16,
+            gain: 1.0,
+            maxAlpha: 0.45,
+            color: [0.58, 0.64, 0.72]
+        },
         model: {
             enabled: false        // legacy full atmosphere model remains off
         },