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>".

tests/ClaudeDo.Worker.Tests/Services/TaskResetServiceTests.cs

@@ -143,6 +143,55 @@ public class TaskResetServiceTests : IDisposable
         Assert.Contains(proxy.Calls, i => i.Method == "WorktreeUpdated" && i.Args[0] is string s && s == task.Id);
     }
 
+    [Fact]
+    public async Task ResetAsync_BroadcastsWorkerLog_ContainingTaskNumber()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+
+        var repo = NewRepo();
+        var db = NewDb();
+        var wtMgr = BuildWorktreeManager(db);
+
+        var list = new ListEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            Name = "reset-number-test",
+            WorkingDir = repo.RepoDir,
+            DefaultCommitType = "feat",
+            CreatedAt = DateTime.UtcNow,
+        };
+        var task = new TaskEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            ListId = list.Id,
+            Title = "numbered task",
+            Number = 321,
+            Status = TaskStatus.Failed,
+            StartedAt = DateTime.UtcNow.AddMinutes(-5),
+            FinishedAt = DateTime.UtcNow.AddMinutes(-1),
+            Result = "some error",
+            CreatedAt = DateTime.UtcNow,
+        };
+
+        using (var ctx = db.CreateContext())
+        {
+            // Bypass TaskRepository.AddAsync — it allocates its own Number via
+            // TaskNumberAllocator and would silently overwrite the one this test sets.
+            ctx.Lists.Add(list);
+            ctx.Tasks.Add(task);
+            await ctx.SaveChangesAsync();
+        }
+
+        var wtCtx = await wtMgr.CreateAsync(task, list, CancellationToken.None);
+        _worktreeCleanups.Add((repo.RepoDir, wtCtx.WorktreePath));
+
+        var (svc, proxy) = BuildService(db, wtMgr);
+        await svc.ResetAsync(task.Id, CancellationToken.None);
+
+        Assert.Contains(proxy.Calls, c => c.Method == "WorkerLog"
+            && c.Args[0] is string s && s.Contains("#321"));
+    }
+
     [Fact]
     public async Task ResetAsync_RunningTask_Throws_AndDoesNotMutate()
     {