fix(worker): allow the done toggle from any non-Running status

MarkDoneAsync was Idle-only, so a finished task (typically a list-handler
run with no worktree to merge) could not be ticked off. Guard on Running
instead and cover the other statuses with tests.

src/ClaudeDo.Worker/State/TaskStateService.cs

@@ -382,14 +382,19 @@ public sealed class TaskStateService : ITaskStateService
     public async Task<TransitionResult> MarkDoneAsync(string taskId, DateTime finishedAt, CancellationToken ct)
     {
         await using var ctx = await _dbFactory.CreateDbContextAsync(ct);
+        // The done toggle is a manual "tick it off" affordance and works from every status
+        // except Running (a live run keeps writing the row, so the picker/runner would race).
+        // WaitingForReview is deliberately included: ticking a finished task done skips the
+        // merge on purpose -- for a worktree-less list-handler task there is nothing to merge,
+        // and for a worktree task the branch just stays Active for the worktrees overview.
         var affected = await ctx.Tasks
-            .Where(t => t.Id == taskId && t.Status == TaskStatus.Idle)
+            .Where(t => t.Id == taskId && t.Status != TaskStatus.Running)
             .ExecuteUpdateAsync(s => s
                 .SetProperty(t => t.Status, TaskStatus.Done)
                 .SetProperty(t => t.FinishedAt, finishedAt), ct);
 
         if (affected == 0)
-            return new TransitionResult(false, "Task is not Idle; cannot mark done.");
+            return new TransitionResult(false, "Task is running or no longer exists; cannot mark done.");
 
         await _broadcaster.TaskUpdated(taskId);
         return new TransitionResult(true, null);