refactor: update color logic in MiningArea to prioritize custom area color

client/src/components/Map3D.jsx

@@ -858,8 +858,9 @@ function MiningArea({ area, turtle, isSelected, onClick }) {
   const centerY = (area.startY + area.endY) / 2;
   const centerZ = (area.startZ + area.endZ) / 2;
 
-  // Color based on turtle or status
+  // Color based on area's custom color, status fallback
   const getColor = () => {
+    if (area.color) return area.color;
     if (area.status === 'completed') return '#10b981'; // green
     if (area.status === 'mining') return '#f59e0b'; // orange
     if (turtle) return turtle.color || '#3b82f6'; // turtle color or blue