feat(ui,worker): surface task numbers in row/detail UI and worker log

Slice 4/5 of task-numbers: TaskRowViewModel.Number renders as a dimmed
"#123" before the row title; DetailsIslandViewModel.TaskIdBadge now
shows "#123" instead of the unusable "#T<guid-prefix>" handle; and the
curated WorkerLog business events in TaskRunner, TaskMergeService, and
TaskResetService prefix their quoted title with "#<Number>".

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

@@ -190,7 +190,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
 
     public string SessionLabel => "claude-session";
 
-    public string TaskIdBadge => Task != null ? $"#T{Task.Id[..Math.Min(3, Task.Id.Length)].ToUpperInvariant()}" : "";
+    public string TaskIdBadge => Task != null ? $"#{Task.Number}" : "";
 
     [ObservableProperty]
     [NotifyCanExecuteChangedFor(nameof(ContinueCommand))]

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

@@ -8,6 +8,7 @@ namespace ClaudeDo.Ui.ViewModels.Islands;
 public sealed partial class TaskRowViewModel : ViewModelBase
 {
     public required string Id { get; init; }
+    [ObservableProperty] private int _number;
     [ObservableProperty] private string _title = "";
     [ObservableProperty] private string _listName = "";
     [ObservableProperty] private bool _done;
@@ -351,6 +352,7 @@ public sealed partial class TaskRowViewModel : ViewModelBase
     public void UpdateFromEntity(TaskEntity t)
     {
         var (add, del) = ParseDiffStat(t.Worktree?.DiffStat);
+        Number            = t.Number;
         Title             = t.Title;
         ListName          = t.List?.Name ?? "";
         Done              = t.Status == TaskStatus.Done;

src/ClaudeDo.Ui/Views/Islands/TaskRowView.axaml

@@ -66,14 +66,18 @@
         <!-- Title + chip row + live tail -->
         <StackPanel Grid.Column="3" Spacing="6" VerticalAlignment="Center">
           <Grid ColumnDefinitions="*,Auto" VerticalAlignment="Center">
-            <TextBlock Grid.Column="0"
-                       Classes="task-title"
-                       Text="{Binding Title}" FontSize="{StaticResource FontSizeTaskTitle}"
-                       Foreground="{DynamicResource TextBrush}"
-                       TextWrapping="Wrap"
-                       FontStyle="{Binding IsDraft, Converter={StaticResource BoolToItalic}}"
-                       Opacity="{Binding IsDraft, Converter={StaticResource BoolToDraftOpacity}}"
-                       TextDecorations="{Binding Done, Converter={StaticResource StrikeIfTrue}}"/>
+            <Grid Grid.Column="0" ColumnDefinitions="Auto,*" VerticalAlignment="Center">
+              <TextBlock Grid.Column="0" Classes="meta" Text="{Binding Number, StringFormat='#{0}'}"
+                         VerticalAlignment="Center" Margin="0,0,6,0"/>
+              <TextBlock Grid.Column="1"
+                         Classes="task-title"
+                         Text="{Binding Title}" FontSize="{StaticResource FontSizeTaskTitle}"
+                         Foreground="{DynamicResource TextBrush}"
+                         TextWrapping="Wrap"
+                         FontStyle="{Binding IsDraft, Converter={StaticResource BoolToItalic}}"
+                         Opacity="{Binding IsDraft, Converter={StaticResource BoolToDraftOpacity}}"
+                         TextDecorations="{Binding Done, Converter={StaticResource StrikeIfTrue}}"/>
+            </Grid>
 
             <!-- Badges: DRAFT and planning session -->
             <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="4"