feat: Phase 5 - polish, validation, rate limiting, Dutch translations

lang/en/public.php

@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+return [
+    'register_button' => 'Register',
+];

lang/nl.json

@@ -0,0 +1,18 @@
+{
+    "First name": "Voornaam",
+    "Last name": "Achternaam",
+    "Email": "E-mailadres",
+    "Phone": "Mobiel",
+    "Register": "Registreren",
+    "days": "dagen",
+    "day": "dag",
+    "hrs": "uur",
+    "mins": "minuten",
+    "secs": "seconden",
+    "Sending…": "Bezig met verzenden…",
+    "Something went wrong. Please try again.": "Er ging iets mis. Probeer het opnieuw.",
+    "This pre-registration period has ended.": "Deze preregistratieperiode is afgelopen.",
+    "Visit ticket shop": "Ga naar de ticketshop",
+    "Thank you for registering!": "Bedankt voor je registratie!",
+    "You are already registered for this event.": "Je bent al geregistreerd voor dit evenement."
+}

lang/nl/public.php

@@ -0,0 +1,7 @@
+<?php
+
+declare(strict_types=1);
+
+return [
+    'register_button' => 'Registreer nu!',
+];