refactor: hashing service (#21997)

* download only backup selected assets

* android impl

* fix tests

* limit concurrent hashing to 16

* extension cleanup

* optimized hashing

* hash only selected albums

* remove concurrency limit

* address review comments

* log more info on failure

* add native cancellation

* small batch size on ios, large on android

* fix: get correct resources

* cleanup getResource

* ios better hash cancellation

* handle graceful cancellation android

* do not trigger multiple hashing ops

* ios: fix circular reference, improve cancellation

* kotlin: more cancellation checks

* no need to create result

* cancel previous task

* avoid race condition

* ensure cancellation gets called

* fix cancellation not happening

---------

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>
Co-authored-by: mertalev <101130780+mertalev@users.noreply.github.com>
Co-authored-by: Alex <alex.tran1502@gmail.com>

mobile/lib/domain/services/background_worker.service.dart

@@ -184,6 +184,7 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
 
     try {
       final backgroundSyncManager = _ref.read(backgroundSyncProvider);
+      final nativeSyncApi = _ref.read(nativeSyncApiProvider);
       _isCleanedUp = true;
       _ref.dispose();
 
@@ -199,7 +200,7 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
         _drift.close(),
         _driftLogger.close(),
         backgroundSyncManager.cancel(),
-        backgroundSyncManager.cancelLocal(),
+        nativeSyncApi.cancelHashing(),
       ];
 
       if (_isar.isOpen) {