feat(suff): disable new user registration post-festival

New usernames now show a "party is over" page instead of proceeding to
account creation. Existing users can still log in. Extended BOOKING_END
to 2026-06-17 23:59 to allow edits through Wednesday night.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gaehsnitz/suff.py

@@ -24,7 +24,7 @@ ANONYMOUS_USERNAME = "anonym"
 BERLIN = ZoneInfo("Europe/Berlin")
 # Festival window: 2026-05-30 10:00 – 2026-06-14 22:00 Berlin time.
 BOOKING_START = datetime(2026, 5, 30, 10, 0, 0, tzinfo=BERLIN)
-BOOKING_END = datetime(2026, 6, 14, 22, 0, 0, tzinfo=BERLIN)
+BOOKING_END = datetime(2026, 6, 17, 23, 59, 0, tzinfo=BERLIN)
 
 DAY_BY_WEEKDAY = {3: 1, 4: 2, 5: 3, 6: 4}
 DAY_CUTOFF_HOUR = 6
@@ -177,9 +177,11 @@ def name_view(request):
                 existing = None
 
             if existing is None:
-                request.session["pending_username"] = username
-                request.session["pending_mode"] = "create"
-                return HttpResponseRedirect(reverse("suff:pin"))
+                return render(
+                    request,
+                    "suff/party_over.html",
+                    {"phase": phase, "username": username},
+                )
 
             if not existing.pin:
                 if _user_has_activity(existing):

gaehsnitz/templates/suff/party_over.html

@@ -0,0 +1,15 @@
+{% extends "suff/base.html" %}
+
+{% block content %}
+<h2>Party vorbei!</h2>
+<p>
+    Der Name <b>{{ username }}</b> existiert noch nicht &mdash;
+    neue Accounts können nicht mehr angelegt werden, weil das Festival vorbei ist.
+</p>
+<p>
+    Du hast schon einen Account? Gib deinen Namen nochmal ein.
+</p>
+<div class="link-row">
+    <a href="{% url 'suff:name' %}" class="link-btn">Zurück</a>
+</div>
+{% endblock %}