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).

packages/features/newsletter/package.json

@@ -33,5 +33,8 @@
     "react": "catalog:",
     "react-hook-form": "catalog:",
     "zod": "catalog:"
+  },
+  "dependencies": {
+    "lucide-react": "catalog:"
   }
-}
+}

packages/features/newsletter/src/components/create-template-dialog.tsx

@@ -0,0 +1,82 @@
+'use client';
+
+import { useAction } from 'next-safe-action/hooks';
+import { useRouter } from 'next/navigation';
+import { useState } from 'react';
+
+import { Plus, Loader2 } from 'lucide-react';
+
+import { Button } from '@kit/ui/button';
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+  DialogTrigger,
+} from '@kit/ui/dialog';
+import { Input } from '@kit/ui/input';
+import { Label } from '@kit/ui/label';
+import { toast } from '@kit/ui/sonner';
+import { Textarea } from '@kit/ui/textarea';
+
+import { createTemplate } from '../server/actions/newsletter-actions';
+
+interface CreateTemplateDialogProps {
+  accountId: string;
+}
+
+export function CreateTemplateDialog({ accountId }: CreateTemplateDialogProps) {
+  const router = useRouter();
+  const [open, setOpen] = useState(false);
+  const [form, setForm] = useState({ name: '', subject: '', bodyHtml: '<h1>Betreff</h1>\n<p>Inhalt hier...</p>' });
+
+  const action = useAction(createTemplate, {
+    onSuccess: () => {
+      toast.success('Vorlage erstellt');
+      setOpen(false);
+      setForm({ name: '', subject: '', bodyHtml: '<h1>Betreff</h1>\n<p>Inhalt hier...</p>' });
+      router.refresh();
+    },
+    onError: () => toast.error('Fehler beim Erstellen'),
+  });
+
+  return (
+    <Dialog open={open} onOpenChange={setOpen}>
+      <DialogTrigger asChild>
+        <Button><Plus className="mr-2 h-4 w-4" />Neue Vorlage</Button>
+      </DialogTrigger>
+      <DialogContent className="max-w-lg">
+        <DialogHeader>
+          <DialogTitle>Newsletter-Vorlage erstellen</DialogTitle>
+          <DialogDescription>Erstellen Sie eine wiederverwendbare Vorlage für Ihren Newsletter.</DialogDescription>
+        </DialogHeader>
+        <div className="grid gap-4 py-4">
+          <div className="grid gap-2">
+            <Label>Name *</Label>
+            <Input placeholder="z.B. Monatlicher Vereinsbrief" value={form.name} onChange={(e) => setForm(s => ({ ...s, name: e.target.value }))} />
+          </div>
+          <div className="grid gap-2">
+            <Label>Betreff *</Label>
+            <Input placeholder="z.B. Neuigkeiten aus dem Verein" value={form.subject} onChange={(e) => setForm(s => ({ ...s, subject: e.target.value }))} />
+          </div>
+          <div className="grid gap-2">
+            <Label>Inhalt (HTML) *</Label>
+            <Textarea rows={6} value={form.bodyHtml} onChange={(e) => setForm(s => ({ ...s, bodyHtml: e.target.value }))} />
+          </div>
+        </div>
+        <DialogFooter>
+          <Button variant="outline" onClick={() => setOpen(false)}>Abbrechen</Button>
+          <Button
+            onClick={() => action.execute({ accountId, name: form.name, subject: form.subject, bodyHtml: form.bodyHtml })}
+            disabled={action.isPending || !form.name || !form.subject || !form.bodyHtml}
+          >
+            {action.isPending && <Loader2 className="mr-2 h-4 w-4 animate-spin" />}
+            Erstellen
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}

packages/features/newsletter/src/components/index.ts

@@ -1 +1,2 @@
 export { CreateNewsletterForm } from './create-newsletter-form';
+export { CreateTemplateDialog } from './create-template-dialog';