fix: expand map filters by default to show hotspot toggle

Make the filters panel expanded by default so users can immediately
see and access the hotspot visualization toggle without needing to
click to expand the panel first.

src/components/map/MapFilters.tsx

@@ -24,7 +24,7 @@ export function MapFilters({
   showHotspots = false,
   isLoadingHotspots = false,
 }: MapFiltersProps) {
-  const [isExpanded, setIsExpanded] = useState(false);
+  const [isExpanded, setIsExpanded] = useState(true);
 
   const litterTypes: LitterType[] = ['plastic', 'metal', 'glass', 'organic', 'hazardous', 'other'];
   const quantities: QuantityLevel[] = ['minimal', 'moderate', 'significant', 'severe'];