feat(mission-control): Handler-Run per Knopf abbrechen

Ein "Abandon run"-Knopf an Handler-Panes fragt HandlerRoundState.Get(handlerTaskId)
nach den noch offenen (Queued/Running) Tasks des Laufs, bestaetigt mit Anzahl,
cancelt jeden ueber den bestehenden CancelTaskAsync-Pfad und schliesst danach die
Session -- ein Schritt statt Tile schliessen + Queue separat abbrechen. Ohne
offene Tasks (oder ohne Round-Eintrag) schliesst die Aktion direkt, ohne Dialog.
Nur an den beiden Handler-Panes sichtbar (IsListHandler), normale Task-/Ad-hoc-
Panes bleiben unveraendert.

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -73,6 +73,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
     private readonly TicketClientFactory _ticketClients;
     private readonly TicketImportService _ticketImport;
     private readonly HandlerRestartCoordinator? _handlerRestart;
+    private readonly HandlerRoundState? _roundState;
 
     public WorkerHub(
         QueueService queue,
@@ -112,7 +113,8 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         TicketPatStore ticketPat = null!,
         TicketClientFactory ticketClients = null!,
         TicketImportService ticketImport = null!,
-        HandlerRestartCoordinator? handlerRestart = null)
+        HandlerRestartCoordinator? handlerRestart = null,
+        HandlerRoundState? roundState = null)
     {
         _queue = queue;
         _waker = waker;
@@ -152,6 +154,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         _ticketClients = ticketClients;
         _ticketImport = ticketImport;
         _handlerRestart = handlerRestart;
+        _roundState = roundState;
     }
 
     // Persistence boundary for the session_skills JSON-array columns (task/list/global).
@@ -810,6 +813,24 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
         _ = _handlerRestart.OnSessionExitedAsync(taskId, exitCode, CancellationToken.None);
     }
 
+    // The Mission Control "abandon run" action: what a handler round queued/started that is still
+    // open (Queued or Running), read from the structured HandlerRoundState store rather than
+    // parsed out of the handler task's description. Empty when there is no round entry (7-day
+    // retention, or a run from before this feature) or the round has no open tasks -- the caller
+    // treats both as "nothing to confirm, just close the pane".
+    public async Task<IReadOnlyList<HandlerOpenTaskDto>> GetHandlerOpenTasks(string handlerTaskId)
+    {
+        var round = _roundState?.Get(handlerTaskId);
+        if (round is not { TaskIds.Count: > 0 }) return Array.Empty<HandlerOpenTaskDto>();
+
+        await using var ctx = await _dbFactory.CreateDbContextAsync();
+        return await ctx.Tasks.AsNoTracking()
+            .Where(t => round.TaskIds.Contains(t.Id)
+                     && (t.Status == TaskStatus.Queued || t.Status == TaskStatus.Running))
+            .Select(t => new HandlerOpenTaskDto(t.Id, t.Title))
+            .ToListAsync();
+    }
+
     // Starts a planning session (worktree + prompt files + token, task -> Planning) and returns
     // the launch spec for an embedded ConPTY planning terminal -- the ConPTY replacement for
     // StartPlanningSessionAsync's external wt window. On any spec-build failure the just-started