weather: add rain and snow screen overlays

config.js

@@ -118,6 +118,29 @@ window.CONFIG = {
         // weatherSimProfile: { rain: { code: 80, tempC: 9, precipMm: 2.0, windKmh: 28 } }
     },
 
+    // ------------------------------------------------------------------
+    // Weather effects
+    // ------------------------------------------------------------------
+    // Visual precipitation overlays driven by window.__currentWeather.
+    // intensity multiplies Open-Meteo values; maxAlpha caps the overlay.
+    weatherEffects: {
+        enabled: true,
+        rain: {
+            enabled: true,
+            intensity: 1.0,       // 0.5 subtle, 2.0 heavy
+            maxAlpha: 0.35,       // maximum screen overlay opacity
+            speed: 1.0            // fall speed multiplier
+        },
+        snow: {
+            enabled: true,
+            intensity: 1.0,
+            maxAlpha: 0.45,
+            speed: 0.35           // slow drifting flakes
+        }
+        // weatherEffects: { enabled: false }
+        // weatherEffects: { rain: { maxAlpha: 0.55, speed: 1.4 }, snow: { enabled: false } }
+    },
+
     // ------------------------------------------------------------------
     // Weather data
     // ------------------------------------------------------------------