Add privacy-friendly analytics and cookie consent, integrated into the CMS

Adds a first-party analytics system with no third-party trackers and no
persistent per-visitor identifiers: events are grouped into sessions via a
daily-rotating pseudonymous hash (IP+UA+host, HMAC-salted, never stored raw).

- New "Analytics" section in the Payload admin, gated by a canViewAnalytics
  permission on Users, following the existing custom-admin-view pattern
  used by the calendar feature
- Sessions, page views, unique visitors, top/entry/exit pages, events,
  device/browser breakdown, date range filter with period comparison
- Raw events and daily aggregate rollups as their own collections, with
  configurable retention and a cron endpoint that rolls up before purging
- Cookie consent banner (necessary/preferences/statistics) with categories
  and copy editable from a new CMS global; a track() helper that is a
  complete no-op without statistics consent, so nothing is ever sent
  before a visitor opts in
- track() calls wired into the booking flow, contact form, and navigation

components/admin/AnalyticsNavLink.tsx

@@ -0,0 +1,30 @@
+import Link from "next/link";
+import type { ServerProps } from "payload";
+import { canViewAnalytics } from "@/access";
+
+export function AnalyticsNavLink({ user }: ServerProps) {
+  // Payload's custom views/nav links have no declarative `access` option —
+  // this component must gate itself (see also AdminAnalyticsView.tsx, which
+  // re-checks the same thing for direct navigation to /admin/analytics).
+  if (!canViewAnalytics({ req: { user } } as Parameters<typeof canViewAnalytics>[0])) return null;
+
+  return (
+    <div style={{ padding: "0 8px 8px" }}>
+      <Link
+        href="/admin/analytics"
+        style={{
+          display: "block",
+          padding: "8px 12px",
+          borderRadius: 6,
+          fontSize: 13,
+          fontWeight: 600,
+          color: "#8b616d",
+          textDecoration: "none",
+          border: "1px solid #e2e2e2",
+        }}
+      >
+        📊 Analytics
+      </Link>
+    </div>
+  );
+}