Make clouds2d.js theme-agnostic

- Remove all hardcoded fallback hex/rgb values
- Skip draw until __currentPalette is published by parent
- applyWeatherTheme now also mixes cloudShadow (was dropped)

background.html

@@ -1416,6 +1416,9 @@ window.weatherThemes = {
             return {
                 sky: mixColor(c.sky, themeColors.skyColor, mix),
                 cloud: mixColor(c.cloud, themeColors.cloudColor, mix),
+                cloudShadow: c.cloudShadow !== undefined
+                    ? mixColor(c.cloudShadow, themeColors.cloudColor, mix * 0.8)
+                    : mixColor(c.cloud, themeColors.cloudColor, mix * 0.8),
                 light: mixColor(c.sun, themeColors.lightColor, mix * 0.5),
                 bg: mixColor(c.bg, themeColors.backgroundColor, mix)
             };
@@ -1645,6 +1648,11 @@ window.weatherThemes = {
             var t = (Date.now() - startTime) / CYCLE % 1;
             var c = getColor(t);
             c = applyWeatherTheme(c);
+            // Expose current palette + weather info for the 2D renderer
+            window.__currentPalette = c;
+            window.__currentWeatherName = currentWeatherThemeName;
+            window.__currentDayProgress = realDayProgress;
+            window.__currentThemeSpeed = currentThemeSpeed;
             effect.setOptions({
                 skyColor: c.sky,
                 cloudColor: c.cloud,