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/dashboard/staff/ticket-scanning/page.tsx

@@ -6,6 +6,7 @@ import { useAuth } from "@/hooks/useAuth";
 import { apiFetch } from "@/lib/api";
 import { useDismissingState } from "@/hooks/useDismissingState";
 import { useRouter } from "next/navigation";
+import { QrCode } from "lucide-react";
 
 export default function TicketScanningPage() {
   const router = useRouter();
@@ -246,9 +247,14 @@ export default function TicketScanningPage() {
     <div className="max-w-6xl mx-auto w-full p-4">
       <div className="grid lg:grid-cols-3 gap-6">
         <div className="lg:col-span-2">
-          <div className="flex items-center justify-between mb-4">
-            <h1 className="text-2xl font-semibold">Ticket Scanning</h1>
-            <button className="px-3 py-1.5 text-sm rounded bg-gray-100 hover:bg-gray-200 text-gray-800 shadow-sm" onClick={() => router.push('/dashboard')}>Back</button>
+          <div className="flex items-center justify-between mb-4 flex-wrap gap-3">
+            <div className="flex items-center gap-3">
+              <div className="w-10 h-10 rounded-xl bg-brand-50 flex items-center justify-center shrink-0">
+                <QrCode className="w-5 h-5 text-brand-600" />
+              </div>
+              <h1 className="text-2xl font-semibold text-gray-900">Ticket Scanning</h1>
+            </div>
+            <button className="px-3 py-1.5 text-sm rounded-lg bg-gray-100 hover:bg-gray-200 text-gray-800 shadow-sm" onClick={() => router.push('/dashboard')}>Back</button>
           </div>
           <p className="text-sm text-gray-600 mb-4">
             Use the button to start/stop scanning. The back camera will be used when available.
@@ -363,7 +369,7 @@ export default function TicketScanningPage() {
       {confirmModal && (
         <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50 p-4">
           <div className="bg-white rounded-xl shadow-lg max-w-md w-full p-6">
-            <h3 className="text-lg font-semibold mb-1 text-indigo-700">Confirm Scan</h3>
+            <h3 className="text-lg font-semibold mb-1 text-brand-700">Confirm Scan</h3>
             <p className="text-sm text-gray-500 mb-4">Review the ticket details before confirming.</p>
 
             <div className="bg-gray-50 border rounded-lg p-4 mb-4 space-y-1 text-sm">
@@ -382,7 +388,7 @@ export default function TicketScanningPage() {
                   inputMode="numeric"
                   min={1}
                   max={confirmModal.remaining}
-                  className="w-24 border rounded px-3 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-indigo-400"
+                  className="w-24 border rounded px-3 py-1.5 text-sm focus:outline-none focus:ring-2 focus:ring-brand-400"
                   value={confirmQtyRaw}
                   onChange={e => setConfirmQtyRaw(e.target.value)}
                   onBlur={() => {
@@ -404,7 +410,7 @@ export default function TicketScanningPage() {
               </button>
               <button
                 onClick={commitScan}
-                className="flex-1 px-4 py-2 rounded-lg bg-indigo-600 text-white text-sm font-semibold hover:bg-indigo-700"
+                className="flex-1 px-4 py-2 rounded-lg bg-brand-600 text-white text-sm font-semibold hover:bg-brand-700"
               >
                 Confirm Scan
               </button>