fix(worker): emit RunCreated after run row exists

Remove premature RunCreated broadcast from WorkerHub.RunNow and the
duplicate calls in RunAsync retry block and ContinueAsync. RunOnceAsync
now owns the broadcast for every run, fired immediately after the row
insert so the UI never receives an event for a non-existent row.

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -37,7 +37,6 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         try
         {
             await _queue.RunNow(taskId);
-            await _broadcaster.RunCreated(taskId, 1, false);
         }
         catch (InvalidOperationException)
         {