fix: preserve stack primary asset selection (#31380)

* fix: preserve stack primary asset selection

* test: select stacked assets by id

* chore: limit dart formatting changes

* fix: address stack viewer review feedback

* fix: align stack ordering with server

* fix: keep stack primary asset first

---------

Co-authored-by: Daniel Dietzler <36593685+danieldietzler@users.noreply.github.com>
(cherry picked from commit 5a5d7be11084969c3c00a294ce6c0527042f88e7)

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

@@ -60,7 +60,6 @@ class AssetService {
     }
 
     final stack = await _remoteRepository.getStackChildren(asset);
-    // Include the primary asset in the stack as the first item
     return [asset, ...stack];
   }
 

mobile/lib/infrastructure/repositories/remote_asset.repository.dart

@@ -76,7 +76,7 @@ class RemoteAssetRepository extends DatabaseAccessor<Drift> with $RemoteAssetRep
 
     final query = _db.remoteAssetEntity.select()
       ..where((row) => row.stackId.equals(stackId) & row.id.equals(asset.id).not())
-      ..orderBy([(row) => OrderingTerm.desc(row.createdAt)]);
+      ..orderBy([(row) => OrderingTerm.asc(row.createdAt)]);
 
     return query.map((row) => row.toDto()).get();
   }

mobile/test/medium/repositories/remote_asset_repository_test.dart

@@ -18,6 +18,37 @@ void main() {
     await ctx.dispose();
   });
 
+  group('getStackChildren', () {
+    test('returns stack children from oldest to newest', () async {
+      final user = await ctx.newUser();
+      const stackId = 'stack';
+      final primary = await ctx.newRemoteAsset(
+        id: 'primary',
+        ownerId: user.id,
+        stackId: stackId,
+        createdAt: DateTime(2026, 1, 2),
+      );
+      final beforePrimary = await ctx.newRemoteAsset(
+        id: 'before-primary',
+        ownerId: user.id,
+        stackId: stackId,
+        createdAt: DateTime(2026, 1, 1),
+      );
+      final afterPrimary = await ctx.newRemoteAsset(
+        id: 'after-primary',
+        ownerId: user.id,
+        stackId: stackId,
+        createdAt: DateTime(2026, 1, 3),
+      );
+      await ctx.newRemoteAsset(ownerId: user.id, stackId: 'other-stack');
+
+      final primaryAsset = await sut.get(primary.id);
+      final stack = await sut.getStackChildren(primaryAsset!);
+
+      expect(stack.map((asset) => asset.id), [beforePrimary.id, afterPrimary.id]);
+    });
+  });
+
   group('getByChecksum', () {
     late String userId;