clouds: retune weather coverage and make night follow weather

vendor/clouds3d.js

@@ -5912,20 +5912,30 @@ function hex(rgb) {
 // Cloud density per weather (0 = clear, 1 = overcast).
 // Names mirror the weather themes defined in background.html.
 var WEATHER_DENSITY = {
-    sunny: 0.20,
-    cloudy: 0.70,
+    sunny: 0.25,
+    cloudy: 0.50,
     // rain and storm both map to 'stormy' (open-meteo codes 51-67, 71-77,
     // 80-86, 95+). Full 1.0 packed the deck so hard that the march showed
     // its own layering, so the top end is capped below overcast.
-    stormy: 0.80,
-    night: 0.45
+    stormy: 0.80
 };
+var LAST_NON_NIGHT_CLOUD_DENSITY = WEATHER_DENSITY.cloudy;
 if (window.CONFIG && window.CONFIG.clouds && window.CONFIG.clouds.density) {
     for (var _wd in window.CONFIG.clouds.density) {
+        // Night follows the last non-night weather density instead of having
+        // its own independent cloud coverage.
+        if (_wd === 'night') continue;
         var _wv = window.CONFIG.clouds.density[_wd];
         if (typeof _wv === 'number') WEATHER_DENSITY[_wd] = Math.max(0, Math.min(1, _wv));
     }
 }
+if (typeof WEATHER_DENSITY.cloudy === 'number') LAST_NON_NIGHT_CLOUD_DENSITY = WEATHER_DENSITY.cloudy;
+function cloudDensityForWeather(weather) {
+    var d = (weather && WEATHER_DENSITY[weather] !== undefined) ? WEATHER_DENSITY[weather] : null;
+    if (d === null || weather === 'night') return LAST_NON_NIGHT_CLOUD_DENSITY;
+    LAST_NON_NIGHT_CLOUD_DENSITY = d;
+    return d;
+}
 
 var moonTexture = null, moonTexFailed = false;
 function loadMoonTexture(gl) {
@@ -6086,8 +6096,7 @@ window.clouds3dRender = function(target) {
     gl.uniform3fv(s.uLight, hex(pal.light));
     gl.uniform3fv(s.uBg, hex(pal.bg));
 
-    var density = (weather && WEATHER_DENSITY[weather] !== undefined)
-        ? WEATHER_DENSITY[weather] : 0.5;
+    var density = cloudDensityForWeather(weather);
     gl.uniform1f(s.uDensity, density);
 
     var day = (typeof dayProgress === 'number')