feat(analytics): Umami integration with per-port admin settings

Adds /[portSlug]/website-analytics dashboard page (pageviews, top
pages, top referrers) and a per-port admin config UI for the
Umami URL / website-ID / API token. Settings live in system_settings
keyed per-port so a future second port has its own Umami account.
Adds a website glance tile to the main dashboard, a server-side
test-credentials endpoint, and a stable cache key for the active-
visitor poll so React Query doesn't fragment the cache per range.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/analytics/range.ts

@@ -0,0 +1,76 @@
+/**
+ * Pure date-range types and helpers shared by client components and the
+ * server-side analytics service.
+ *
+ * Lives outside `src/lib/services/analytics.service.ts` because that file
+ * imports the DB driver (`postgres`) which can't be bundled into client
+ * components - see Next.js "Module not found: net" build error.
+ *
+ * No DB / no IO / no React.
+ */
+
+/**
+ * Preset date ranges used by the dashboard's quick-pick tabs.
+ */
+export type PresetDateRange = '7d' | '30d' | '90d' | 'today';
+
+/**
+ * A custom date range expressed as a pair of ISO date strings (YYYY-MM-DD).
+ * The lower bound is inclusive at 00:00; the upper bound is inclusive at
+ * 23:59:59.999 (resolved inside `rangeToBounds`).
+ */
+export interface CustomDateRange {
+  kind: 'custom';
+  from: string; // ISO YYYY-MM-DD
+  to: string; // ISO YYYY-MM-DD
+}
+
+export type DateRange = PresetDateRange | CustomDateRange;
+
+export const ALL_RANGES: readonly PresetDateRange[] = ['today', '7d', '30d', '90d'] as const;
+
+export function isCustomRange(range: DateRange): range is CustomDateRange {
+  return typeof range === 'object' && range.kind === 'custom';
+}
+
+/**
+ * Resolve any DateRange (preset or custom) to a concrete {from, to} pair.
+ * - Preset ranges anchor `to` at "now" and `from` at `now - N days`.
+ * - Custom ranges use the operator-supplied dates verbatim, with `to`
+ *   normalized to end-of-day so a same-day range still includes that day.
+ */
+export function rangeToBounds(range: DateRange): { from: Date; to: Date } {
+  if (isCustomRange(range)) {
+    return {
+      from: new Date(`${range.from}T00:00:00.000Z`),
+      to: new Date(`${range.to}T23:59:59.999Z`),
+    };
+  }
+  const now = Date.now();
+  const days = rangeToDays(range);
+  return { from: new Date(now - days * 86_400_000), to: new Date(now) };
+}
+
+export function rangeToDays(range: PresetDateRange): number {
+  switch (range) {
+    case 'today':
+      return 1;
+    case '7d':
+      return 7;
+    case '30d':
+      return 30;
+    case '90d':
+      return 90;
+  }
+}
+
+/**
+ * Number of days a range spans (rounded up). Useful for sizing chart axes.
+ */
+export function rangeSpanDays(range: DateRange): number {
+  if (isCustomRange(range)) {
+    const { from, to } = rangeToBounds(range);
+    return Math.max(1, Math.ceil((to.getTime() - from.getTime()) / 86_400_000));
+  }
+  return rangeToDays(range);
+}