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/supervisor/manual-registration/page.tsx

@@ -5,6 +5,7 @@ import { useAuth } from "@/hooks/useAuth";
 import { useRouter } from "next/navigation";
 import { apiFetch } from "@/lib/api";
 import { useDismissingState } from "@/hooks/useDismissingState";
+import { UserPlus } from "lucide-react";
 
 type FormField = { id: string; type: 'yes_no'|'text'|'date'|'numeric'|'statement'|'paragraph'; label: string; isRequired?: boolean; helpText?: string|null };
 
@@ -61,7 +62,12 @@ export default function ManualRegistrationPage() {
 
   return (
     <div className="max-w-xl">
-      <h1 className="text-xl font-semibold mb-4">Manual Registration</h1>
+      <div className="flex items-center gap-3 mb-4">
+        <div className="w-10 h-10 rounded-xl bg-brand-50 flex items-center justify-center shrink-0">
+          <UserPlus className="w-5 h-5 text-brand-600" />
+        </div>
+        <h1 className="text-xl font-semibold text-gray-900">Manual Registration</h1>
+      </div>
       <form onSubmit={submit} className="space-y-3">
         <div>
           <label className="block text-sm font-medium">Event ID</label>
@@ -96,7 +102,7 @@ export default function ManualRegistrationPage() {
         </div>
         <p className="text-xs text-gray-500">At least one of email or cell number is required. If no email is provided, a guest account is created automatically.</p>
         {error && <p className="text-sm text-red-600">{error}</p>}
-        <button type="submit" disabled={busy} className="bg-blue-600 text-white rounded px-4 py-2 disabled:opacity-60">
+        <button type="submit" disabled={busy} className="bg-brand-600 hover:bg-brand-700 text-white rounded px-4 py-2 disabled:opacity-60">
           {busy ? "Submitting..." : "Create"}
         </button>
       </form>
@@ -198,7 +204,7 @@ function AttendeeFormsSection({ registration, form, formsData, setFormsData }: {
           </div>
         ))}
       </div>
-      <button className="mt-3 px-3 py-1.5 text-sm rounded bg-indigo-600 text-white hover:bg-indigo-700 disabled:opacity-50" disabled={submitting || !canSubmit} onClick={submit}>{submitting ? 'Submitting…' : 'Submit forms'}</button>
+      <button className="mt-3 px-3 py-1.5 text-sm rounded bg-brand-600 text-white hover:bg-brand-700 disabled:opacity-50" disabled={submitting || !canSubmit} onClick={submit}>{submitting ? 'Submitting…' : 'Submit forms'}</button>
     </div>
   );
 }