Refactor frontend date formatting helpers and mark Task 10 done

frontend/src/utils/formatDate.ts

@@ -130,3 +130,34 @@ export function formatRelative(
     return formatDate(isoUtc, timezone);
   }
 }
+
+/**
+ * Format an ISO 8601 timestamp for display with local browser timezone.
+ *
+ * Keeps parity with existing code paths in the UI that render full date+time
+ * strings inside table rows.
+ */
+export function formatTimestamp(iso: string): string {
+  try {
+    return new Date(iso).toLocaleString(undefined, {
+      year: "numeric",
+      month: "2-digit",
+      day: "2-digit",
+      hour: "2-digit",
+      minute: "2-digit",
+      second: "2-digit",
+    });
+  } catch {
+    return iso;
+  }
+}
+
+/**
+ * Format a duration in seconds to a compact text representation.
+ */
+export function formatSeconds(seconds: number): string {
+  if (seconds < 0) return "permanent";
+  if (seconds < 60) return `${String(seconds)} s`;
+  if (seconds < 3600) return `${String(Math.round(seconds / 60))} min`;
+  return `${String(Math.round(seconds / 3600))} h`;
+}