feat(worker): report worktree-creation phase on OperationProgress

Fills the silent gap between Queued and the first agent output: WorktreeManager
now broadcasts a "creating_worktree" phase (before the initial git worktree add
and again for the self-heal retry section) through the existing OperationProgress
channel, and the task row shows it via the pre-existing but unused
ops.worker.creatingWorktree locale key until the next entity refresh clears it.

Confirmed the 2026-08-07 triage finding still holds: TaskRunner already
broadcasts WorktreeUpdated right after WorktreeManager.CreateAsync
(TaskRunner.cs:342-346, :501) -- no second broadcast added there.

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

@@ -143,6 +143,12 @@
               <TextBlock Text="{Binding StatusLabel}"/>
             </Border>
 
+            <!-- Transient creation-phase chip: fills the silent gap between Queued and the
+                 first agent output while the worker creates this task's worktree. -->
+            <Border Classes="chip chip-tag" IsVisible="{Binding HasCreationPhase}">
+              <TextBlock Text="{Binding CreationPhaseLabel}"/>
+            </Border>
+
             <!-- Dequeue button (visible when row is Queued, or planning parent has queued subtasks) -->
             <Button Classes="icon-btn dequeue-btn"
                     IsVisible="{Binding CanRemoveFromQueue}"