feat: persistent recent files history + fix limit enforcement + fix settings data loss

- Recent files are now persisted to disk and survive restarts
- Max items limit is applied on load (in case setting was reduced)
- Omitted paths regex filtering is now wired up in addToRecentFiles
- Fixed saveAndRefresh() overwriting entire plugin data on settings change
- Debounced disk writes (300ms) to avoid excessive saves on rapid opens

manifest.json

@@ -1,7 +1,7 @@
 {
 	"id": "waypoint-sidebar",
 	"name": "Waypoint Sidebar",
-	"version": "1.3.0",
+	"version": "1.4.0",
 	"minAppVersion": "0.16.3",
 	"description": "Calendar, recent files, and custom bookmarks sidebar.",
 	"author": "Olivier",