Improve delete UX and prepaid credit time display.

Show minutes and local expiry for resource credits; add shared delete hook with row/card loading overlays, detail-page deleting modal, and disabled controls to prevent double-delete.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/format-utils.ts

@@ -18,3 +18,25 @@ export function parseMemoryToMi(mem: string): number {
   if (mem.endsWith('Ki')) return parseFloat(mem) / 1024;
   return parseFloat(mem);
 }
+
+/** Human-readable time left (days, hours, minutes). */
+export function formatRemainingDurationMs(remainingMs: number): string {
+  const ms = Math.max(0, remainingMs);
+  const days = Math.floor(ms / 86400000);
+  const hours = Math.floor((ms % 86400000) / 3600000);
+  const minutes = Math.floor((ms % 3600000) / 60000);
+  if (days > 0) return `${days}d ${hours}h ${minutes}m`;
+  if (hours > 0) return `${hours}h ${minutes}m`;
+  if (minutes > 0) return `${minutes}m`;
+  return 'less than 1m';
+}
+
+/** Expiry timestamp in the user's locale and timezone. */
+export function formatExpiresAtLocal(expiresAt: string | Date): string {
+  const date = typeof expiresAt === 'string' ? new Date(expiresAt) : expiresAt;
+  if (Number.isNaN(date.getTime())) return '—';
+  return date.toLocaleString(undefined, {
+    dateStyle: 'medium',
+    timeStyle: 'short',
+  });
+}