Add security middleware, audit log, alerts, PayPal, cron, radio + apps

Security (launch blockers):
- src/middleware.ts (edge): forwards x-pathname + real client IP.
- access-guard.ts (Node, from root layout): routes non-staff to /maintenance
  when maintenance mode is on, banned users to /banned. New /banned + /maintenance
  pages (the consumers the admin toggle was missing). Admin layout enforces
  force_staff_2fa before /admin.
- staff-activity.ts audit log wired into ban/lift/give-currency/set-rank actions.

Infra (parallel agents): alert service (alert_logs + Discord embed + email),
PayPal top-up (create/capture API routes + /shop/topup), cron worker
(scripts/jobs-worker.ts via croner: emulator-ping->alert, maintenance-check,
bans-cleanup), social connections page, admin radio settings/banners/ranks.
Public radio subsystem: /radio (+schedule, shouts+post, contests, giveaways,
apply, leaderboard) and /apply/staff + /apply/team submission forms. Radio nav
link added. .env.example documents the new optional vars.

(radio song-requests dropped: its table is a stub in AtomCMS — columns added by
un-modeled alter-migrations.)

Verified: tsc exit 0, vitest 48/48, next build exit 0 (82 page routes).

src/components/navigation.tsx

@@ -78,6 +78,9 @@ export async function Navigation() {
           </div>
         </details>
 
+        <Link href="/radio" className="nav-item">
+          Radio
+        </Link>
         {session?.user ? (
           <Link href="/friends" className="nav-item">
             Friends