Add close X button to filter popover

Add X button in top-right corner to close filter dropdown

src/components/ColumnFilterPopover.tsx

@@ -161,6 +161,13 @@ export function ColumnFilterPopover({
       )}
       onClick={(e) => e.stopPropagation()}
     >
+      <button
+        onClick={onClose}
+        className="absolute top-2 right-2 text-slate-500 hover:text-white p-1 rounded transition-colors z-10"
+      >
+        <X className="w-4 h-4" />
+      </button>
+
       {title && <div className="text-[10px] font-bold text-slate-500 uppercase tracking-wider px-1">{title}</div>}
 
       <div className="flex gap-1 border-b border-slate-700 pb-2">