feat(portal): M10.1 — fill the 10 customer-area shells

Four real surfaces wired to tenant-registry (settings, settings/api-keys CRUD, audit pagination, products live entitlements), five forward-looking empty states with CTAs. 56 vitest tests + 10 Playwright canaries. lib/format.ts consolidates date helpers.

Refs: M10.1

src/lib/format.ts

@@ -0,0 +1,56 @@
+// Lightweight date/time helpers — shared across server components so we
+// don't reinvent toLocaleString conventions per page.
+
+export function formatRelative(iso: string, now: number = Date.now()): string {
+  const t = new Date(iso).getTime();
+  if (Number.isNaN(t)) return iso;
+  const diff = t - now;
+  const abs = Math.abs(diff);
+  const ago = diff < 0;
+  const units: [string, number][] = [
+    ["second", 1000],
+    ["minute", 60 * 1000],
+    ["hour", 3600 * 1000],
+    ["day", 24 * 3600 * 1000],
+    ["week", 7 * 24 * 3600 * 1000],
+    ["month", 30 * 24 * 3600 * 1000],
+    ["year", 365 * 24 * 3600 * 1000],
+  ];
+  let unit = "second";
+  let n = Math.round(abs / 1000);
+  for (let i = units.length - 1; i >= 0; i--) {
+    if (abs >= units[i][1]) {
+      unit = units[i][0];
+      n = Math.round(abs / units[i][1]);
+      break;
+    }
+  }
+  const suffix = n === 1 ? unit : `${unit}s`;
+  return ago ? `${n} ${suffix} ago` : `in ${n} ${suffix}`;
+}
+
+export function formatDateTime(iso: string): string {
+  const d = new Date(iso);
+  if (Number.isNaN(d.getTime())) return iso;
+  // YYYY-MM-DD HH:MM:SS — locale-stable, sortable, no surprises.
+  const pad = (n: number) => String(n).padStart(2, "0");
+  return (
+    d.getUTCFullYear() +
+    "-" +
+    pad(d.getUTCMonth() + 1) +
+    "-" +
+    pad(d.getUTCDate()) +
+    " " +
+    pad(d.getUTCHours()) +
+    ":" +
+    pad(d.getUTCMinutes()) +
+    ":" +
+    pad(d.getUTCSeconds()) +
+    " UTC"
+  );
+}
+
+export function truncate(s: string, max = 40): string {
+  if (s.length <= max) return s;
+  return s.slice(0, max - 1) + "…";
+}