fix: show neutral badge for categories without assigned colors

- Categories without colors now show gray badge instead of no badge
- Categories with colors show colored badge as before
- Bump version to 0.2.0

package.json

@@ -1,7 +1,7 @@
 {
   "name": "nextcloud-notes-tauri",
   "private": true,
-  "version": "0.1.5",
+  "version": "0.2.0",
   "type": "module",
   "scripts": {
     "dev": "vite",