mitigatin CORS problems on api endpoint

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

de.srsoftware.cal.web/src/main/java/de/srsoftware/cal/ApiEndpoint.java

@@ -94,6 +94,7 @@ public class ApiEndpoint extends PathHandler {
 		String hostname = hostname(ex);
 		String urlTemplate = hostname+"/static/event?id={}";
 		String prodId = "OpenCloudCal@"+hostname.split("://",2)[1];
+		ex.getResponseHeaders().add("Access-Control-Allow-Origin","*");
 		return switch (path) {
 			case "/event" -> sendContent(ex,getEvent(ex).map(ApiEndpoint::toJson).map(ApiEndpoint::httpError));
 			case "/event/ical"-> sendContent(ex,getEvent(ex).map(event -> toIcal(event, hostname, urlTemplate)).map(ical -> Util.wrapIcal(ical,prodId)).map(ApiEndpoint::httpError));