chore : move all to root

nest-front/src/utils/format.ts

@@ -0,0 +1,47 @@
+/**
+ * Format an ISO 8601 date string to a human-readable date.
+ */
+export function formatDate(iso: string): string {
+  return new Date(iso).toLocaleDateString('en-US', {
+    year: 'numeric',
+    month: 'short',
+    day: 'numeric',
+  });
+}
+
+/**
+ * Format an ISO 8601 date string to a human-readable datetime.
+ */
+export function formatDateTime(iso: string): string {
+  return new Date(iso).toLocaleString('en-US', {
+    year: 'numeric',
+    month: 'short',
+    day: 'numeric',
+    hour: '2-digit',
+    minute: '2-digit',
+  });
+}
+
+/**
+ * Return a relative time string (e.g. "3 days ago").
+ */
+export function timeAgo(iso: string): string {
+  const diff = Date.now() - new Date(iso).getTime();
+  const seconds = Math.floor(diff / 1000);
+  if (seconds < 60) return 'just now';
+  const minutes = Math.floor(seconds / 60);
+  if (minutes < 60) return `${minutes}m ago`;
+  const hours = Math.floor(minutes / 60);
+  if (hours < 24) return `${hours}h ago`;
+  const days = Math.floor(hours / 24);
+  if (days < 30) return `${days}d ago`;
+  return formatDate(iso);
+}
+
+/**
+ * Truncate a string to maxLength and append ellipsis.
+ */
+export function truncate(str: string, maxLength: number): string {
+  if (str.length <= maxLength) return str;
+  return str.slice(0, maxLength).trimEnd() + '...';
+}