Add weather simulation + debug-panel weather controls

- weatherSim config flag (default false): cycles through
  ['sunny','cloudy','stormy','night'] every weatherSimInterval ms
  instead of pulling open-meteo
- Debug-panel buttons: Sunny / Cloudy / Stormy / Night for
  instant manual switch; Auto-Cycle toggle, Stop, 5s/15s cycle
- Cleanup: removed duplicate unwrapped tick() in the init block
  (the wrapped one already starts the rAF chain)

The sim keeps the existing 5-minute palette transition between
states, so you still see the colour shift rather than a hard cut.

config.js

@@ -94,4 +94,12 @@ window.THEMES = {
     'ash': 'ash.css',
     'gruvbox': 'gruvbox.css',
     'nord': 'nord.css'
+
+    // weatherSim     - If true, ignore open-meteo and cycle through
+    //                   ['sunny', 'cloudy', 'stormy', 'night'] automatically
+    //                   every weatherSimInterval ms. Useful for testing
+    //                   every theme without waiting on the API.
+    // weatherSimInterval - Sim cycle period in ms (default 30000).
+    weatherSim: false,
+    weatherSimInterval: 30000,
 };