feat: gate registration behind 16 March 2026 19:00 opening date

- Add REGISTRATION_OPENS_AT const in lib/opening.ts as single source of truth
- Add useRegistrationOpen hook with live 1s countdown ticker
- Add CountdownBanner component (DD/HH/MM/SS) with canvas-confetti on open
- EventRegistrationForm shows countdown instead of form while closed
- Login page hides/disables signup while closed; login always available
- WatcherForm AccountModal guards signUp call as defence-in-depth

Closes #2

apps/web/src/routes/login.tsx

@@ -12,6 +12,8 @@ import {
 } from "@/components/ui/card";
 import { Input } from "@/components/ui/input";
 import { authClient } from "@/lib/auth-client";
+import { REGISTRATION_OPENS_AT } from "@/lib/opening";
+import { useRegistrationOpen } from "@/lib/useRegistrationOpen";
 import { orpc } from "@/utils/orpc";
 
 export const Route = createFileRoute("/login")({
@@ -31,6 +33,7 @@ export const Route = createFileRoute("/login")({
 function LoginPage() {
 	const navigate = useNavigate();
 	const search = Route.useSearch();
+	const { isOpen } = useRegistrationOpen();
 	const [isSignup, setIsSignup] = useState(() => search.signup === "1");
 	const [email, setEmail] = useState(() => search.email ?? "");
 	const [password, setPassword] = useState("");
@@ -204,6 +207,43 @@ function LoginPage() {
 								← Terug naar website
 							</Link>
 						</div>
+					) : isSignup && !isOpen ? (
+						/* Signup is closed until registration opens */
+						<div className="space-y-4">
+							<div className="rounded-lg border border-white/10 bg-white/5 p-5 text-center">
+								<p className="mb-1 font-['Intro',sans-serif] text-white">
+									Registratie nog niet open
+								</p>
+								<p className="text-sm text-white/60">
+									Accounts aanmaken kan vanaf{" "}
+									<span className="text-teal-300">
+										{REGISTRATION_OPENS_AT.toLocaleDateString("nl-BE", {
+											weekday: "long",
+											day: "numeric",
+											month: "long",
+										})}{" "}
+										om{" "}
+										{REGISTRATION_OPENS_AT.toLocaleTimeString("nl-BE", {
+											hour: "2-digit",
+											minute: "2-digit",
+										})}
+									</span>
+									.
+								</p>
+							</div>
+							<div className="flex flex-col gap-2 text-center">
+								<button
+									type="button"
+									onClick={() => setIsSignup(false)}
+									className="text-sm text-white/60 hover:text-white"
+								>
+									Al een account? Log in
+								</button>
+								<Link to="/" className="text-sm text-white/60 hover:text-white">
+									← Terug naar website
+								</Link>
+							</div>
+						</div>
 					) : (
 						<form onSubmit={handleSubmit} className="space-y-4">
 							{isSignup && (
@@ -271,15 +311,29 @@ function LoginPage() {
 										: "Inloggen"}
 							</Button>
 							<div className="flex flex-col gap-2 text-center">
-								<button
-									type="button"
-									onClick={() => setIsSignup(!isSignup)}
-									className="text-sm text-white/60 hover:text-white"
-								>
-									{isSignup
-										? "Al een account? Log in"
-										: "Nog geen account? Registreer"}
-								</button>
+								{/* Only show signup toggle when registration is open */}
+								{isOpen && (
+									<button
+										type="button"
+										onClick={() => setIsSignup(!isSignup)}
+										className="text-sm text-white/60 hover:text-white"
+									>
+										{isSignup
+											? "Al een account? Log in"
+											: "Nog geen account? Registreer"}
+									</button>
+								)}
+								{!isOpen && isSignup === false && (
+									<button
+										type="button"
+										onClick={() => setIsSignup(true)}
+										className="cursor-not-allowed text-sm text-white/30"
+										disabled
+										title="Registratie opent op 16 maart om 19:00"
+									>
+										Nog geen account? (opent 16 maart)
+									</button>
+								)}
 								<Link to="/" className="text-sm text-white/60 hover:text-white">
 									← Terug naar website
 								</Link>