feat(ui): editable task status and tags from details panel

Adds a status ComboBox in the Details header (no transition guards)
and a Tags section with chips + AutoCompleteBox. TaskRowViewModel.Tags
becomes an ObservableCollection so chip lists stay live. TasksIsland
caches AllTags for the row context menu and exposes Set/Toggle helpers.
Test fakes updated for the new IWorkerClient methods.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
 using ClaudeDo.Data.Models;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
@@ -7,6 +8,11 @@ namespace ClaudeDo.Ui.ViewModels.Islands;
 
 public sealed partial class TaskRowViewModel : ViewModelBase
 {
+    public TaskRowViewModel()
+    {
+        Tags.CollectionChanged += (_, _) => OnPropertyChanged(nameof(HasTags));
+    }
+
     public required string Id { get; init; }
     [ObservableProperty] private string _title = "";
     [ObservableProperty] private string _listName = "";
@@ -33,7 +39,7 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     public DateTime CreatedAt { get; init; }
     public string CreatedAtFormatted => CreatedAt == default ? "—" : $"Created {CreatedAt:MMM d}";
 
-    public IReadOnlyList<string> Tags { get; init; } = Array.Empty<string>();
+    public ObservableCollection<string> Tags { get; } = new();
     public int StepsCount { get; init; }
     public int StepsCompleted { get; init; }
 
@@ -154,6 +160,15 @@ public sealed partial class TaskRowViewModel : ViewModelBase
         DiffDeletions     = del;
         ParentTaskId      = t.ParentTaskId;
         BlockedByTaskId   = t.BlockedByTaskId;
+        SetTags(t.Tags.Select(tag => tag.Name));
+    }
+
+    public void SetTags(IEnumerable<string> names)
+    {
+        var snapshot = names.ToList();
+        if (Tags.SequenceEqual(snapshot)) return;
+        Tags.Clear();
+        foreach (var n in snapshot) Tags.Add(n);
     }
 
     // Best-effort parse of diff stat strings like "+12 -3" or "12 additions, 3 deletions".