Full site redesign, help system, and dashboard stats fixes

Multi-phase visual facelift (design tokens, dashboards, sidebar/navbar
shell, per-page help guides, and a layout/content pass across every
remaining page) plus backend fixes to the dashboard KPI stats:

- Admin/Supervisor dashboard KPIs (revenue, donations, registrations,
  tickets sold) now use a rolling trailing-month window (today back one
  calendar month, e.g. 9 May - 8 June if today is 8 June) instead of
  calendar month-to-date, which under-counted for most of the month.
  The comparison window shifts the same way, so like is still compared
  with like.
- Reports deep-links from those stat tiles now match the same window
  (range=trailing_month, replacing range=this_month).
- Design tokens (brand-* Tailwind scale + shadcn CSS variables), a
  site-wide contextual help button, fixed dashboard sidebar/navbar,
  Admin/Supervisor/Staff/User dashboard rebuilds backed by a new
  GET /api/stats/overview endpoint, a dedicated Contact page, Site
  Settings restyle with WhatsApp config folded in, and an Account
  activity feed backed by a new SecurityEvent model.
- Every remaining page (home, events, registration flow, auth, legal,
  payment results, and every Admin/Supervisor/Staff/User tool page)
  restyled onto the same design tokens, several with real layout
  upgrades (home hero, events list/detail, donate page, auth pages).
- 20+ new dedicated help guides so the whole site has page-specific
  help content instead of falling back to a generic guide.
- Assorted fixes surfaced along the way: donation-leg double-counting
  in payment stats, donations not counting toward revenue, refund
  netting in per-method report breakdowns, and donation
  over-allocation after a refund.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/src/utils/securityEvents.js

@@ -0,0 +1,34 @@
+const prisma = require('../config/db');
+const { describeUserAgent } = require('./userAgent');
+
+// Fire-and-forget by design — a logging failure must never break login/password-change,
+// so this swallows its own errors rather than propagating them to the caller (same
+// posture as the existing email/WhatsApp notification sends elsewhere in this codebase).
+async function logSecurityEvent({ userId, type, ip, userAgent }) {
+  try {
+    await prisma.securityEvent.create({
+      data: {
+        userId: userId || null,
+        type,
+        ip: ip || null,
+        device: describeUserAgent(userAgent),
+      },
+    });
+  } catch (e) {
+    console.error('Failed to log security event:', e?.message);
+  }
+}
+
+// Recent activity for a user's Profile & Security page — no raw IP in the response,
+// just what the mockup shows (what happened, on what device, when).
+async function getRecentSecurityEvents(userId, limit = 10) {
+  const rows = await prisma.securityEvent.findMany({
+    where: { userId },
+    orderBy: { createdAt: 'desc' },
+    take: limit,
+    select: { id: true, type: true, device: true, createdAt: true },
+  });
+  return rows;
+}
+
+module.exports = { logSecurityEvent, getRecentSecurityEvents };