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>

frontend/src/app/events/page.tsx

@@ -2,6 +2,7 @@ import { Navbar } from "@/components/layout/Navbar";
 import { Footer } from "@/components/layout/Footer";
 import { EventCard } from "@/components/events/EventCard";
 import { apiFetch } from "@/lib/api";
+import { Calendar, CalendarX } from "lucide-react";
 
 export const revalidate = 60;
 
@@ -33,9 +34,20 @@ export default async function EventsPage() {
     <div className="min-h-screen flex flex-col">
       <Navbar />
       <main className="flex-1 py-10 px-4 max-w-7xl mx-auto w-full">
-        <h1 className="text-3xl font-bold mb-6">All Events</h1>
+        <div className="flex items-center gap-3 mb-8">
+          <div className="w-11 h-11 rounded-xl bg-brand-50 flex items-center justify-center shrink-0">
+            <Calendar className="w-6 h-6 text-brand-600" />
+          </div>
+          <div>
+            <h1 className="text-2xl sm:text-3xl font-bold text-gray-900">All Events</h1>
+            <p className="text-sm text-gray-500">{sorted.length} upcoming event{sorted.length === 1 ? "" : "s"}</p>
+          </div>
+        </div>
         {sorted.length === 0 ? (
-          <p className="text-gray-600">No events available.</p>
+          <div className="text-center py-16 border rounded-xl bg-gray-50">
+            <CalendarX className="w-8 h-8 text-gray-300 mx-auto mb-2" />
+            <p className="text-gray-500 text-sm">No events available right now — check back soon.</p>
+          </div>
         ) : (
           <div className="grid gap-6 md:grid-cols-3 sm:grid-cols-2">
             {sorted.map((event) => (