feat(frontend): dashboard and stats pages

packages/frontend/src/lib/format.ts

@@ -0,0 +1,12 @@
+export function formatDuration(seconds: number): string {
+  const h = Math.floor(seconds / 3600);
+  const m = Math.floor((seconds % 3600) / 60);
+  const s = seconds % 60;
+  if (h > 0) return `${h}u ${m}m`;
+  if (m > 0) return `${m}m ${s}s`;
+  return `${s}s`;
+}
+export function formatPct(n: number): string { return `${Math.round(n * 100)}%`; }
+export function formatDate(unixSec: number): string {
+  return new Date(unixSec * 1000).toLocaleString();
+}