Update: preserve UltraHand .offload state (overlays/packages)

- Add folder_copy_switch_update_offload_aware() for update-only switch copy
- If item exists in .overlays/.offload or .packages/.offload, update in place; else copy to main
- Remove sd:/switch/.overlays from update delete list so .offload survives
- Fresh install unchanged (no offload logic)

Co-authored-by: Cursor <cursoragent@cursor.com>

source/deletion_lists_update.h

@@ -122,9 +122,8 @@ static const char* config_dirs_to_delete[] = {
 };
 
 // Switch directories to delete
-// NOTE: .packages is intentionally excluded - UltraHand package cache, preserve during updates
+// NOTE: .overlays and .packages excluded - preserve UltraHand .offload hide state during updates
 static const char* switch_dirs_to_delete[] = {
-    "sd:/switch/.overlays",
     "sd:/switch/90DNS_tester",
     "sd:/switch/aio-switch-updater",
     "sd:/switch/amsPLUS-downloader",