Add asset sorting and favorites-only filter for notifications

New notification settings for "assets added" events:
- Sort Assets By: date, rating, name, or original order
- Sort Direction: ascending or descending
- Notify Favorites Only: filter to only favorite assets

Rating sort handles null values by placing unrated assets last
(descending) or first (ascending).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

manifest.json

@@ -1,3 +1,3 @@
 {
-  "version": "1.25.0"
+  "version": "1.26.0"
 }