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/AnalyticsChart.tsx

@@ -0,0 +1,35 @@
+"use client";
+
+import { CartesianGrid, Line, LineChart, ResponsiveContainer, Tooltip, XAxis, YAxis } from "recharts";
+import type { DailyPoint } from "@/lib/analytics/dashboardQueries";
+
+const ACCENT = "#8b616d"; // matches the existing admin CSS modules' accent color
+const ACCENT_MUTED = "#c9a8ae";
+
+function fmtDay(iso: string): string {
+  return new Date(`${iso}T00:00:00Z`).toLocaleDateString("de-DE", { day: "2-digit", month: "2-digit" });
+}
+
+export function AnalyticsChart({ series }: { series: DailyPoint[] }) {
+  if (series.length === 0) {
+    return <p style={{ color: "#888", fontSize: 14 }}>Noch keine Daten in diesem Zeitraum.</p>;
+  }
+
+  const data = series.map((p) => ({ ...p, label: fmtDay(p.date) }));
+
+  return (
+    <ResponsiveContainer width="100%" height={260}>
+      <LineChart data={data} margin={{ top: 8, right: 16, bottom: 0, left: 0 }}>
+        <CartesianGrid stroke="#eee" vertical={false} />
+        <XAxis dataKey="label" tick={{ fontSize: 12, fill: "#888" }} axisLine={{ stroke: "#e2e2e2" }} tickLine={false} />
+        <YAxis tick={{ fontSize: 12, fill: "#888" }} axisLine={false} tickLine={false} allowDecimals={false} width={36} />
+        <Tooltip
+          contentStyle={{ borderRadius: 8, border: "1px solid #e2e2e2", fontSize: 13 }}
+          labelFormatter={(label) => `Tag: ${label}`}
+        />
+        <Line type="monotone" dataKey="pageViews" name="Seitenaufrufe" stroke={ACCENT} strokeWidth={2} dot={false} />
+        <Line type="monotone" dataKey="sessions" name="Sessions" stroke={ACCENT_MUTED} strokeWidth={2} dot={false} />
+      </LineChart>
+    </ResponsiveContainer>
+  );
+}