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

src/components/board/CardThumbnail.tsx

@@ -0,0 +1,57 @@
+import { format, isPast, isToday } from "date-fns";
+import type { Card, Label } from "@/types/board";
+import { LabelDots } from "@/components/board/LabelDots";
+import { ChecklistBar } from "@/components/board/ChecklistBar";
+
+interface CardThumbnailProps {
+  card: Card;
+  boardLabels: Label[];
+}
+
+export function CardThumbnail({ card, boardLabels }: CardThumbnailProps) {
+  const hasDueDate = card.dueDate != null;
+  const dueDate = hasDueDate ? new Date(card.dueDate!) : null;
+  const overdue = dueDate != null && isPast(dueDate) && !isToday(dueDate);
+
+  function handleClick() {
+    // Card detail modal will be wired in Task 11
+    console.log("Card clicked:", card.id);
+  }
+
+  return (
+    <button
+      onClick={handleClick}
+      className="w-full rounded-lg bg-pylon-surface p-3 shadow-sm text-left transition-all duration-200 hover:-translate-y-px hover:shadow-md"
+    >
+      {/* Label dots */}
+      {card.labels.length > 0 && (
+        <div className="mb-2">
+          <LabelDots labelIds={card.labels} boardLabels={boardLabels} />
+        </div>
+      )}
+
+      {/* Card title */}
+      <p className="text-sm font-medium text-pylon-text">{card.title}</p>
+
+      {/* Footer row: due date + checklist */}
+      {(hasDueDate || card.checklist.length > 0) && (
+        <div className="mt-2 flex items-center gap-3">
+          {dueDate && (
+            <span
+              className={`font-mono text-xs ${
+                overdue
+                  ? "rounded bg-pylon-danger/10 px-1 py-0.5 text-pylon-danger"
+                  : "text-pylon-text-secondary"
+              }`}
+            >
+              {format(dueDate, "MMM d")}
+            </span>
+          )}
+          {card.checklist.length > 0 && (
+            <ChecklistBar checklist={card.checklist} />
+          )}
+        </div>
+      )}
+    </button>
+  );
+}

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>
+  );
+}

src/components/board/LabelDots.tsx

@@ -0,0 +1,37 @@
+import {
+  Tooltip,
+  TooltipTrigger,
+  TooltipContent,
+} from "@/components/ui/tooltip";
+import type { Label } from "@/types/board";
+
+interface LabelDotsProps {
+  labelIds: string[];
+  boardLabels: Label[];
+}
+
+export function LabelDots({ labelIds, boardLabels }: LabelDotsProps) {
+  if (labelIds.length === 0) return null;
+
+  const labels = labelIds
+    .map((id) => boardLabels.find((l) => l.id === id))
+    .filter((l): l is Label => l != null);
+
+  if (labels.length === 0) return null;
+
+  return (
+    <div className="flex items-center gap-1">
+      {labels.map((label) => (
+        <Tooltip key={label.id}>
+          <TooltipTrigger asChild>
+            <span
+              className="inline-block size-2 shrink-0 rounded-full"
+              style={{ backgroundColor: label.color }}
+            />
+          </TooltipTrigger>
+          <TooltipContent>{label.name}</TooltipContent>
+        </Tooltip>
+      ))}
+    </div>
+  );
+}