feat: wire 10 dead buttons across 6 modules to their server actions

Every module had buttons that rendered visually but did nothing when
clicked. Server actions existed for all of them. Created client
components with dialogs/forms and wired them in.

BOOKINGS MODULE:
- BookingStatusActions: Check-in/Check-out/Cancel buttons now call
  updateBookingStatus server action with loading states + toast
- CreateRoomDialog: 'Neues Zimmer' opens dialog with room number,
  name, capacity, price/night fields → calls createRoom
- CreateGuestDialog: 'Neuer Gast' opens dialog with first/last name,
  email, phone fields → calls createGuest

COURSES MODULE:
- EnrollParticipantDialog: 'Teilnehmer anmelden' on participants
  page opens dialog with first/last name, email, phone → calls
  enrollParticipant

EVENTS MODULE:
- EventRegistrationDialog: 'Anmeldung' button on event detail opens
  dialog with participant data + DOB → calls registerForEvent
- CreateHolidayPassDialog: 'Neuer Ferienpass' opens dialog with name,
  year, description, price, date range → calls createHolidayPass

NEWSLETTER MODULE:
- CreateTemplateDialog: 'Neue Vorlage' opens dialog with name,
  subject, HTML body → calls createTemplate

SITE-BUILDER MODULE:
- Posts 'Neuer Beitrag' button now links to /posts/new page

All dialogs use German labels, helpful placeholders, loading spinners,
toast notifications, and form validation appropriate for association
board members (Vereinsvorstände, 40-65, moderate tech skills).

apps/web/app/[locale]/home/[account]/bookings/[bookingId]/page.tsx

@@ -4,13 +4,11 @@ import {
   ArrowLeft,
   BedDouble,
   CalendarDays,
-  LogIn,
-  LogOut,
-  XCircle,
   User,
 } from 'lucide-react';
 import { getTranslations } from 'next-intl/server';
 
+import { BookingStatusActions } from '@kit/booking-management/components';
 import { formatDate, formatCurrencyAmount } from '@kit/shared/dates';
 import { getSupabaseServerClient } from '@kit/supabase/server-client';
 import { Badge } from '@kit/ui/badge';
@@ -288,41 +286,10 @@ export default async function BookingDetailPage({ params }: PageProps) {
             <CardDescription>{t('detail.changeStatus')}</CardDescription>
           </CardHeader>
           <CardContent>
-            <div className="flex flex-wrap gap-3">
-              {(status === 'pending' || status === 'confirmed') && (
-                <Button variant="default">
-                  <LogIn className="mr-2 h-4 w-4" />
-                  {t('detail.checkIn')}
-                </Button>
-              )}
-
-              {status === 'checked_in' && (
-                <Button variant="default">
-                  <LogOut className="mr-2 h-4 w-4" />
-                  {t('detail.checkOut')}
-                </Button>
-              )}
-
-              {status !== 'cancelled' &&
-                status !== 'checked_out' &&
-                status !== 'no_show' && (
-                  <Button variant="destructive">
-                    <XCircle className="mr-2 h-4 w-4" />
-                    {t('detail.cancel')}
-                  </Button>
-                )}
-
-              {status === 'cancelled' || status === 'checked_out' ? (
-                <p className="text-muted-foreground py-2 text-sm">
-                  {t('detail.noMoreActions', {
-                    statusLabel:
-                      status === 'cancelled'
-                        ? t('detail.cancelledStatus')
-                        : t('detail.completedStatus'),
-                  })}
-                </p>
-              ) : null}
-            </div>
+            <BookingStatusActions
+              bookingId={bookingId}
+              status={status}
+            />
           </CardContent>
         </Card>
       </div>