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/activate-account/page.tsx

@@ -5,6 +5,7 @@ import { Footer } from "@/components/layout/Footer";
 import { apiFetch } from "@/lib/api";
 import { useSearchParams, useRouter } from "next/navigation";
 import { appName } from "@/lib/siteConfig";
+import { ShieldCheck } from "lucide-react";
 
 function ActivateAccountContent() {
   const search = useSearchParams();
@@ -42,7 +43,12 @@ function ActivateAccountContent() {
       <Navbar />
       <main className="flex-1 px-4 py-10 max-w-md mx-auto w-full">
         <div className="border rounded-xl p-6 bg-white shadow-sm">
-          <h1 className="text-2xl font-semibold mb-2">Activate your account</h1>
+          <div className="flex items-center gap-3 mb-2">
+            <div className="w-10 h-10 rounded-xl bg-brand-50 flex items-center justify-center shrink-0">
+              <ShieldCheck className="w-5 h-5 text-brand-600" />
+            </div>
+            <h1 className="text-2xl font-semibold text-gray-900">Activate your account</h1>
+          </div>
           <p className="text-gray-500 text-sm mb-5">Set a password to activate your {appName} account.</p>
           {!token && <p className="text-red-600 mb-4">Missing or invalid activation link.</p>}
           <form onSubmit={submit} className="space-y-4">
@@ -58,7 +64,7 @@ function ActivateAccountContent() {
             {password && confirm && password !== confirm && (
               <p className="text-xs text-red-600">Passwords do not match.</p>
             )}
-            <button disabled={loading || !canSubmit} className="px-4 py-2 rounded bg-blue-600 text-white disabled:opacity-60 w-full py-2.5 font-medium">
+            <button disabled={loading || !canSubmit} className="px-4 py-2 rounded bg-brand-600 hover:bg-brand-700 text-white disabled:opacity-60 w-full py-2.5 font-medium">
               {loading ? "Activating…" : "Activate my account"}
             </button>
           </form>