Revert "feat: terrain-following cloud base"

This reverts commit 3e17279499.

config.js

@@ -335,14 +335,6 @@ window.CONFIG = {
             start: 0.35,          // world units: clouds fade out very close to camera
             end: 2.5              // full density from this distance onward
         },
-        // Terrain-following cloud base. The DEM height grid is sampled in
-        // the cloud shader, so the cloud bottom rises locally to keep a
-        // clearance above the visible ground. 'bottom' remains the global
-        // floor for areas without terrain data.
-        groundFollow: {
-            enabled: true,        // false = flat cloud deck
-            clearanceM: 50        // metres above terrain, exaggerated with terrain
-        },
         // Coverage per weather level, 0 = clear, 1 = overcast. Only the
         // levels listed here override the built-in defaults
         // (sunny 0.20, cloudy 0.70, stormy 0.80, night 0.45). Live weather