project: reorganize the structure of the project.

* remove dotnet-tool.json because the project does not rely on any dotnet tools.
* remove Directory.Build.props because the solution has only one project.
* move src/SourceGit to src. It's not needed to put all sources into a subfolder of src since there's only one project.

src/ViewModels/StashesPage.cs

@@ -0,0 +1,154 @@
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+using Avalonia.Threading;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace SourceGit.ViewModels
+{
+    public class StashesPage : ObservableObject
+    {
+        public int Count
+        {
+            get => _stashes == null ? 0 : _stashes.Count;
+        }
+
+        public List<Models.Stash> Stashes
+        {
+            get => _stashes;
+            set
+            {
+                if (SetProperty(ref _stashes, value))
+                {
+                    SelectedStash = null;
+                }
+            }
+        }
+
+        public Models.Stash SelectedStash
+        {
+            get => _selectedStash;
+            set
+            {
+                if (SetProperty(ref _selectedStash, value))
+                {
+                    if (value == null)
+                    {
+                        Changes = null;
+                    }
+                    else
+                    {
+                        Task.Run(() =>
+                        {
+                            var changes = new Commands.QueryStashChanges(_repo.FullPath, value.SHA).Result();
+                            Dispatcher.UIThread.Invoke(() =>
+                            {
+                                Changes = changes;
+                            });
+                        });
+                    }
+                }
+            }
+        }
+
+        public List<Models.Change> Changes
+        {
+            get => _changes;
+            private set
+            {
+                if (SetProperty(ref _changes, value))
+                {
+                    SelectedChange = null;
+                }
+            }
+        }
+
+        public Models.Change SelectedChange
+        {
+            get => _selectedChange;
+            set
+            {
+                if (SetProperty(ref _selectedChange, value))
+                {
+                    if (value == null)
+                    {
+                        DiffContext = null;
+                    }
+                    else
+                    {
+                        DiffContext = new DiffContext(_repo.FullPath, new Models.DiffOption($"{_selectedStash.SHA}^", _selectedStash.SHA, value), _diffContext);
+                    }
+                }
+            }
+        }
+
+        public DiffContext DiffContext
+        {
+            get => _diffContext;
+            private set => SetProperty(ref _diffContext, value);
+        }
+
+        public StashesPage(Repository repo)
+        {
+            _repo = repo;
+        }
+
+        public void Cleanup()
+        {
+            _repo = null;
+            if (_stashes != null)
+                _stashes.Clear();
+            _selectedStash = null;
+            if (_changes != null)
+                _changes.Clear();
+            _selectedChange = null;
+            _diffContext = null;
+        }
+
+        public void Apply(object param)
+        {
+            if (param is Models.Stash stash)
+            {
+                Task.Run(() =>
+                {
+                    new Commands.Stash(_repo.FullPath).Apply(stash.Name);
+                });
+            }
+        }
+
+        public void Pop(object param)
+        {
+            if (param is Models.Stash stash)
+            {
+                Task.Run(() =>
+                {
+                    new Commands.Stash(_repo.FullPath).Pop(stash.Name);
+                });
+            }
+        }
+
+        public void Drop(object param)
+        {
+            if (param is Models.Stash stash && PopupHost.CanCreatePopup())
+            {
+                PopupHost.ShowPopup(new DropStash(_repo.FullPath, stash));
+            }
+        }
+
+        public void Clear()
+        {
+            if (PopupHost.CanCreatePopup())
+            {
+                PopupHost.ShowPopup(new ClearStashes(_repo));
+            }
+        }
+
+        private Repository _repo = null;
+        private List<Models.Stash> _stashes = null;
+        private Models.Stash _selectedStash = null;
+        private List<Models.Change> _changes = null;
+        private Models.Change _selectedChange = null;
+        private DiffContext _diffContext = null;
+    }
+}