calendar download, date input validate, nc talk notification

frontend/src/pages/Kalender.tsx

@@ -1807,6 +1807,20 @@ export default function Kalender() {
   }, [bookingForm.fahrzeugId, bookingForm.beginn, bookingForm.ende]);
 
   const handleBookingSave = async () => {
+    if (!isValidGermanDateTime(bookingForm.beginn)) {
+      setBookingDialogError('Ungültiges Beginn-Datum (Format: TT.MM.JJJJ HH:MM)');
+      return;
+    }
+    if (!isValidGermanDateTime(bookingForm.ende)) {
+      setBookingDialogError('Ungültiges Ende-Datum (Format: TT.MM.JJJJ HH:MM)');
+      return;
+    }
+    const beginnIso = fromGermanDateTime(bookingForm.beginn)!;
+    const endeIso = fromGermanDateTime(bookingForm.ende)!;
+    if (new Date(endeIso) <= new Date(beginnIso)) {
+      setBookingDialogError('Ende muss nach dem Beginn liegen');
+      return;
+    }
     setBookingDialogLoading(true);
     setBookingDialogError(null);
     try {
@@ -2216,7 +2230,9 @@ export default function Kalender() {
                 <Button
                   variant="outlined"
                   startIcon={<FileDownloadIcon />}
-                  onClick={() => window.open(icalEventUrl, '_blank')}
+                  component="a"
+                  href={icalEventUrl}
+                  download="veranstaltungen.ics"
                 >
                   Herunterladen
                 </Button>
@@ -2711,7 +2727,9 @@ export default function Kalender() {
                 <Button
                   variant="outlined"
                   startIcon={<FileDownloadIcon />}
-                  onClick={() => window.open(icalBookingUrl, '_blank')}
+                  component="a"
+                  href={icalBookingUrl}
+                  download="buchungen.ics"
                 >
                   Herunterladen
                 </Button>