implemented new filter for tags when requesting list of events:

until now, filtering was done _after_ reading events from the db.
Now we first search viable appointment ids when tags are set and add these to the where clause for the actual request

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

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

@@ -150,7 +150,7 @@ public class ApiEndpoint extends PathHandler {
 		Result<LocalDateTime> end = parseDate(param.get(END));
 		var     endDate = (end == null) ? null: end.optional().orElse(null);
 
-		return db.list(startDate, endDate, count, offset).map(res -> filterByTags(res, tags));
+		return db.list(startDate, endDate, count, offset, tags).map(res -> filterByTags(res, tags));
 	}
 
 	private Result<List<Appointment>> filterByTags(Result<List<Appointment>> res, List<String> tags) {