feat(ui): list reordering, quick actions, and resizable modals

- Drag-to-reorder user lists in the sidebar, persisted via a new
  list sort_order column (AddListSortOrder migration, backfilled by
  creation time) and ListRepository.ReorderAsync
- "Open in Explorer" / "Open in Terminal" context-menu actions on lists
- "Clear all completed" button on the Tasks island
- Inline-edit subtask titles (empty text deletes the step) and
  click-to-copy task ID in the Details island
- Make modal and planning windows resizable (BorderOnly decorations
  with min sizes) instead of fixed-size borderless

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs

@@ -840,6 +840,35 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
         CloseDetail?.Invoke();
     }
 
+    [RelayCommand]
+    private async System.Threading.Tasks.Task CommitSubtaskEditAsync(SubtaskRowViewModel? row)
+    {
+        if (row is null || !row.IsEditing) return;
+        row.IsEditing = false;
+
+        var title = row.Title?.Trim() ?? "";
+        await using var ctx = _dbFactory.CreateDbContext();
+        var repo = new SubtaskRepository(ctx);
+
+        // Emptying the text removes the step.
+        if (string.IsNullOrEmpty(title))
+        {
+            await repo.DeleteAsync(row.Id);
+            Subtasks.Remove(row);
+            return;
+        }
+
+        var subs = await repo.GetByTaskIdAsync(Task?.Id ?? "");
+        var entity = subs.FirstOrDefault(s => s.Id == row.Id);
+        if (entity is null) return;
+        if (entity.Title != title)
+        {
+            entity.Title = title;
+            await repo.UpdateAsync(entity);
+        }
+        row.Title = title;
+    }
+
     [RelayCommand]
     private async System.Threading.Tasks.Task AddSubtaskAsync()
     {
@@ -943,6 +972,7 @@ public sealed partial class SubtaskRowViewModel : ViewModelBase
     public required string Id { get; init; }
     [ObservableProperty] private string _title = "";
     [ObservableProperty] private bool _done;
+    [ObservableProperty] private bool _isEditing;
     [ObservableProperty] private ClaudeDo.Data.Models.TaskStatus _status;
     [ObservableProperty] private ClaudeDo.Data.Models.WorktreeState _worktreeState = ClaudeDo.Data.Models.WorktreeState.Active;
 }

src/ClaudeDo.Ui/ViewModels/Islands/ListNavItemViewModel.cs

@@ -12,6 +12,8 @@ public sealed partial class ListNavItemViewModel : ViewModelBase
     [ObservableProperty] private bool _isActive;
     [ObservableProperty] private string? _workingDir;
     [ObservableProperty] private string _defaultCommitType = CommitTypeRegistry.DefaultType;
+    [ObservableProperty] private bool _dropHintAbove;
+    [ObservableProperty] private bool _dropHintBelow;
     public string? IconKey { get; init; }
     public string? DotColorKey { get; init; }
 }

src/ClaudeDo.Ui/ViewModels/Islands/ListsIslandViewModel.cs

@@ -82,6 +82,52 @@ public sealed partial class ListsIslandViewModel : ViewModelBase
         finally { _worktreesOverviewOpen = false; }
     }
 
+    [RelayCommand]
+    private void OpenInExplorer(ListNavItemViewModel? row)
+    {
+        var dir = row?.WorkingDir;
+        if (string.IsNullOrWhiteSpace(dir) || !System.IO.Directory.Exists(dir)) return;
+        try
+        {
+            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo
+            {
+                FileName = dir,
+                UseShellExecute = true,
+            });
+        }
+        catch { /* best-effort */ }
+    }
+
+    [RelayCommand]
+    private void OpenInTerminal(ListNavItemViewModel? row)
+    {
+        var dir = row?.WorkingDir;
+        if (string.IsNullOrWhiteSpace(dir) || !System.IO.Directory.Exists(dir)) return;
+        try
+        {
+            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo
+            {
+                FileName = "wt.exe",
+                Arguments = $"-d \"{dir}\"",
+                UseShellExecute = true,
+            });
+        }
+        catch
+        {
+            // Windows Terminal not installed — fall back to a plain console at the directory.
+            try
+            {
+                System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo
+                {
+                    FileName = "cmd.exe",
+                    WorkingDirectory = dir,
+                    UseShellExecute = true,
+                });
+            }
+            catch { /* best-effort */ }
+        }
+    }
+
     public ObservableCollection<ListNavItemViewModel> Items { get; } = new();
     public ObservableCollection<ListNavItemViewModel> SmartLists { get; } = new();
     public ObservableCollection<ListNavItemViewModel> UserLists { get; } = new();
@@ -231,6 +277,57 @@ public sealed partial class ListsIslandViewModel : ViewModelBase
         }
     }
 
+    public void ClearDropHints()
+    {
+        foreach (var r in UserLists)
+        {
+            r.DropHintAbove = false;
+            r.DropHintBelow = false;
+        }
+    }
+
+    public void SetDropHint(ListNavItemViewModel target, bool placeBelow)
+    {
+        foreach (var r in UserLists)
+        {
+            var isTarget = ReferenceEquals(r, target);
+            r.DropHintAbove = isTarget && !placeBelow;
+            r.DropHintBelow = isTarget && placeBelow;
+        }
+    }
+
+    public async Task ReorderAsync(ListNavItemViewModel source, ListNavItemViewModel target, bool placeBelow)
+    {
+        if (source.Kind != ListKind.User || target.Kind != ListKind.User) return;
+        if (ReferenceEquals(source, target)) return;
+
+        MoveWithinCollection(UserLists, source, target, placeBelow);
+
+        var orderedIds = UserLists.Select(i => i.Id["user:".Length..]).ToList();
+        await using var ctx = await _dbFactory.CreateDbContextAsync();
+        var lists = new ListRepository(ctx);
+        await lists.ReorderAsync(orderedIds);
+    }
+
+    private static void MoveWithinCollection(
+        ObservableCollection<ListNavItemViewModel> coll,
+        ListNavItemViewModel source,
+        ListNavItemViewModel target,
+        bool placeBelow)
+    {
+        var srcIdx = coll.IndexOf(source);
+        var tgtIdx = coll.IndexOf(target);
+        if (srcIdx < 0 || tgtIdx < 0 || srcIdx == tgtIdx) return;
+
+        var finalIdx = placeBelow ? tgtIdx + 1 : tgtIdx;
+        if (srcIdx < finalIdx) finalIdx--;
+        if (finalIdx < 0) finalIdx = 0;
+        if (finalIdx >= coll.Count) finalIdx = coll.Count - 1;
+        if (finalIdx == srcIdx) return;
+
+        coll.Move(srcIdx, finalIdx);
+    }
+
     partial void OnSelectedListChanged(ListNavItemViewModel? value)
     {
         foreach (var i in Items) i.IsActive = ReferenceEquals(i, value);

src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs

@@ -487,6 +487,38 @@ public sealed partial class TasksIslandViewModel : ViewModelBase
         TasksChanged?.Invoke(this, EventArgs.Empty);
     }
 
+    [RelayCommand]
+    private async Task ClearCompletedAsync()
+    {
+        if (CompletedItems.Count == 0) return;
+
+        // Delete children before parents so the parent-child FK (Restrict) doesn't
+        // block removing a completed planning parent together with its done children.
+        var toDelete = CompletedItems.OrderByDescending(r => r.IsChild).ToList();
+
+        if (ConfirmAsync is not null)
+        {
+            var ok = await ConfirmAsync($"Clear {toDelete.Count} completed task(s)? This cannot be undone.");
+            if (!ok) return;
+        }
+
+        await using var db = await _dbFactory.CreateDbContextAsync();
+        var repo = new TaskRepository(db);
+        foreach (var row in toDelete)
+        {
+            try
+            {
+                await repo.DeleteAsync(row.Id);
+                Items.Remove(row);
+            }
+            catch { /* still referenced by open child tasks; leave it visible */ }
+        }
+
+        Regroup();
+        UpdateSubtitle();
+        TasksChanged?.Invoke(this, EventArgs.Empty);
+    }
+
     [RelayCommand]
     private async Task ToggleStarAsync(TaskRowViewModel row)
     {