Initial commit: Kalendartool (Next.js, Prisma, Docker)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

components/admin/CreateCalendarForm.tsx

@@ -0,0 +1,71 @@
+'use client';
+
+/** Formular zum Erstellen eines Kalenders (nur Admin). */
+import { useState } from 'react';
+import { useRouter } from 'next/navigation';
+import { Button, Card, ErrorMessage, Input, Label } from '@/components/ui/ui';
+
+export function CreateCalendarForm() {
+  const router = useRouter();
+  const [error, setError] = useState<string | null>(null);
+  const [busy, setBusy] = useState(false);
+
+  async function handleSubmit(event: React.FormEvent<HTMLFormElement>) {
+    event.preventDefault();
+    setBusy(true);
+    setError(null);
+
+    const formData = new FormData(event.currentTarget);
+    try {
+      const response = await fetch('/api/calendars', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          title: formData.get('title'),
+          description: formData.get('description') || undefined,
+          timezone: formData.get('timezone'),
+        }),
+      });
+
+      if (!response.ok) {
+        const data = (await response.json()) as { error?: string };
+        setError(data.error ?? 'Erstellen fehlgeschlagen.');
+        return;
+      }
+      router.push('/dashboard');
+      router.refresh();
+    } catch {
+      setError('Netzwerkfehler. Bitte erneut versuchen.');
+    } finally {
+      setBusy(false);
+    }
+  }
+
+  return (
+    <Card>
+      <form onSubmit={handleSubmit} className="space-y-4">
+        <ErrorMessage message={error} />
+        <div>
+          <Label htmlFor="title">Titel</Label>
+          <Input id="title" name="title" type="text" required maxLength={120} />
+        </div>
+        <div>
+          <Label htmlFor="description">Beschreibung (optional)</Label>
+          <Input id="description" name="description" type="text" maxLength={2000} />
+        </div>
+        <div>
+          <Label htmlFor="timezone">Zeitzone</Label>
+          <Input
+            id="timezone"
+            name="timezone"
+            type="text"
+            required
+            defaultValue="Europe/Berlin"
+            maxLength={64}
+          />
+        </div>
+        <Button disabled={busy}>{busy ? 'Erstellen …' : 'Kalender erstellen'}</Button>
+      </form>
+    </Card>
+  );
+}