Implemented negative filters in back-end, added basic fixed filters settings dialog.

src/cache.js

@@ -1,6 +1,10 @@
 import redis from './redis.js';
 
 export async function getIdsBySlug(slugs, domain) {
+	if (!slugs) {
+		return [];
+	}
+
 	const ids = await Promise.all(slugs.map(async (slug) => {
 		if (!slug) {
 			return null;