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/content/help/supervisor-manual.tsx

@@ -0,0 +1,59 @@
+import React from "react";
+import { UserPlus, CreditCard, Info } from "lucide-react";
+import { GuideItem } from "@/components/shared/GuideItem";
+import type { HelpContent } from "./types";
+
+/** Help content for /dashboard/supervisor/manual. */
+export const supervisorManualHelpContent: HelpContent = {
+  title: "Manual registration",
+  subtitle: "Register someone and take payment on their behalf.",
+  tabs: [
+    {
+      key: "register",
+      label: "Register",
+      icon: UserPlus,
+      content: (
+        <div className="space-y-4">
+          <p>Pick an event, then either search for an existing user or enter guest details (name, email, phone) and tick &quot;Guest&quot; to skip linking an account. Choose ticket options and quantities — early-bird pricing is applied automatically — then create the registration.</p>
+          <p className="text-xs text-gray-500">After creating a registration, the Record Payment tab is pre-filled with it — switch tabs to take payment right away.</p>
+        </div>
+      ),
+    },
+    {
+      key: "payment",
+      label: "Record Payment",
+      icon: CreditCard,
+      content: (
+        <div className="space-y-4">
+          <p>Search for a user, pick one of their registrations with an outstanding balance, and enter the amount, method, and (optionally) a backdated payment time.</p>
+        </div>
+      ),
+    },
+  ],
+};
+
+/** Help content for /dashboard/supervisor/manual-registration — the older, simpler form. */
+export const supervisorManualRegistrationLegacyHelpContent: HelpContent = {
+  title: "Manual registration (legacy)",
+  subtitle: "A basic form for creating a registration directly.",
+  quickLinks: [
+    { label: "Manual registration & payment", href: "/dashboard/supervisor/manual", icon: UserPlus },
+  ],
+  tabs: [
+    {
+      key: "overview",
+      label: "Overview",
+      icon: Info,
+      content: (
+        <div className="space-y-4">
+          <p>This is an older, simplified registration form — it requires typing the exact Event ID and Option ID rather than picking from a list, and doesn&apos;t support payment or early-bird pricing.</p>
+          <div className="space-y-4">
+            <GuideItem icon={UserPlus} title="Prefer the newer page" tone="brand">
+              The Manual Registration &amp; Payment page (linked above) offers event/user search, live pricing, and lets you take payment in the same flow — use it unless you specifically need this one.
+            </GuideItem>
+          </div>
+        </div>
+      ),
+    },
+  ],
+};