atmosphere: replace flickering full-screen haze with stable terrain haze

config.js

@@ -317,7 +317,7 @@ window.CONFIG = {
         rayleighGain: 8.0,        // exposure for the physical sky term
         distanceFog: false,       // legacy aerial perspective is off
         haze: {
-            enabled: true,
+            enabled: false,       // full-screen haze pass causes horizon/sky flicker
             heightKm: 100,
             scaleHeightKm: 8.5,
             density: 0.18,
@@ -325,6 +325,14 @@ window.CONFIG = {
             gain: 1.0,
             maxAlpha: 0.55
         },
+        terrainHaze: {
+            enabled: true,
+            scaleHeightKm: 8.5,
+            density: 0.22,
+            gain: 1.0,
+            maxAlpha: 0.65,
+            color: [0.58, 0.64, 0.72]
+        },
         model: {
             enabled: false        // legacy full atmosphere model remains off
         },