add card thumbnails with label dots, due dates, and checklist progress bar

src/components/board/ChecklistBar.tsx

@@ -0,0 +1,22 @@
+import type { ChecklistItem } from "@/types/board";
+
+interface ChecklistBarProps {
+  checklist: ChecklistItem[];
+}
+
+export function ChecklistBar({ checklist }: ChecklistBarProps) {
+  if (checklist.length === 0) return null;
+
+  return (
+    <div className="flex items-center gap-px">
+      {checklist.map((item) => (
+        <span
+          key={item.id}
+          className={`inline-block h-1 w-1.5 rounded-[1px] ${
+            item.checked ? "bg-pylon-accent" : "bg-pylon-column"
+          }`}
+        />
+      ))}
+    </div>
+  );
+}