feat: new layout, rooms row, fix weather+HA, fix BottomNav overflow

- Remove TasksCard and SavingsCard from home tab
- New grid layout: lights+thermostat row 1, purifier+weather row 2
- Add RoomsRow component with room navigation
- Fix HA entity mapping: fan.zhimi_rmb1_9528_air_purifier → fan.air_purifier
- Add real entity aliases for HA route
- Fix weather route: add timeout, better error handling
- Fix BottomNav: use 100dvh + flex-shrink-0
- TopBar: accept isDemo prop, show Demo badge in header
- WeatherCard: compact prop, better loading/error states
- globals.css: add no-scrollbar utility

app/globals.css

@@ -226,3 +226,12 @@ input[type='range']::-moz-range-thumb {
   0%, 100% { transform: translate(0, 0) scale(1); }
   50% { transform: translate(-30px, -20px) scale(1.06); }
 }
+
+/* Hide scrollbar but allow scrolling */
+.no-scrollbar {
+  -ms-overflow-style: none;
+  scrollbar-width: none;
+}
+.no-scrollbar::-webkit-scrollbar {
+  display: none;
+}