feat(worker): emit WorkerLog for merge, discard, reset

src/ClaudeDo.Worker/Services/TaskMergeService.cs

@@ -136,6 +136,7 @@ public sealed class TaskMergeService
         _logger.LogInformation(
             "Merged task {TaskId} branch {Branch} into {Target} (remove worktree: {Remove})",
             taskId, wt.BranchName, targetBranch, removeWorktree);
+        await _broadcaster.WorkerLog($"Merged \"{task.Title}\" into {targetBranch}", WorkerLogLevel.Success, DateTime.UtcNow);
 
         return new MergeResult(StatusMerged, Array.Empty<string>(), cleanupWarning);
     }

src/ClaudeDo.Worker/Services/TaskResetService.cs

@@ -51,6 +51,7 @@ public sealed class TaskResetService
         if (wt is not null && wt.State == WorktreeState.Active && list.WorkingDir is not null)
         {
             await _wtManager.DiscardAsync(wt, list.WorkingDir, ct);
+            await _broadcaster.WorkerLog($"Discarded worktree for \"{task.Title}\"", WorkerLogLevel.Warn, DateTime.UtcNow);
             worktreeChanged = true;
         }
 
@@ -64,5 +65,6 @@ public sealed class TaskResetService
             await _broadcaster.WorktreeUpdated(taskId);
 
         _logger.LogInformation("Reset task {TaskId} to Manual (worktree discarded: {Discarded})", taskId, worktreeChanged);
+        await _broadcaster.WorkerLog($"Reset \"{task.Title}\"", WorkerLogLevel.Warn, DateTime.UtcNow);
     }
 }