terrain: extend map with reduced-resolution outer height skirt

config.js

@@ -235,6 +235,14 @@ window.CONFIG = {
         enabled: true,            // false = flat plane (no DEM, no terrain shadows)
         exaggeration: 8,          // vertical scale (1 = real, nearly invisible here)
         edgeFadeTiles: 4,         // soft rim at the mosaic border, in tiles (~13 km)
+        edgeSkirtKm: 800,         // coarse outer terrain pulled past the horizon
+        edgeSkirtRings: 24,       // coarse rings in the outer skirt
+        edgeSkirtNoise: 0.28,     // fallback height variation if outer DEM is off
+        outerDem: {
+            enabled: true,
+            zoom: 7,              // reduced-resolution terrarium zoom for the skirt
+            maxMeters: 2500       // height normalization for skirt colors
+        },
         carLights: true,          // moving vehicle lights on the real road network
         cityLights: true,         // settlement lights from OSM place nodes
         wireframe: false          // true = draw the mesh edges (orientation debug)