feat(registration): add watcher capacity limits and update pricing

Add 70-person capacity limit for watchers with real-time availability checks.
Update drink card pricing to €5 per person (was €5 base + €2 per guest).
Add feature flag to bypass registration countdown.
Show under-review notice for performer registrations.
Update FAQ performance duration from 5-7 to 5 minutes.

apps/web/src/routes/manage.$token.tsx

@@ -569,7 +569,7 @@ function ManageRegistrationPage() {
 				Jouw inschrijving
 			</h1>
 			<p className="mb-8 text-white/60">
-				Open Mic Night — vrijdag 18 april 2026
+				Open Mic Night — vrijdag 24 april 2026
 			</p>
 
 			{/* Type badge */}