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

src-tauri/tauri.conf.json

@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "Nextcloud Notes",
-  "version": "0.1.5",
+  "version": "0.2.0",
   "identifier": "com.davidrelich.nextcloud-notes",
   "build": {
     "beforeDevCommand": "npm run dev",