fix(merge): pass the stash consent to the conflict resolver so it opens on a dirty target

The resolver restarts the merge via StartConflictMerge, which had no autostash.
After a stash-retry approve reported 'conflict', the restart hit the same dirty
target, got 'dirty_target' and the resolver silently never opened. Thread the
consent through the hub, client, coordinator and resolver; surface a refusal in
the footer instead of dropping it.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs

@@ -1295,9 +1295,11 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             // Nothing landed -- the target working dir has uncommitted changes (often another
             // session's WIP in the shared main checkout). Offer the one-shot stash retry; git
             // restores the changes itself once the merge is through.
+            var stashed = false;
             if (result?.Status == "dirty_target" && Dialogs != null
                 && await Dialogs.ConfirmAsync(Loc.T("vm.detailsIsland.stashAndMergeConfirm")))
             {
+                stashed = true;
                 ApproveOp.Report(Loc.T("ops.merge.merging"));
                 result = await _worker.ApproveReviewAsync(
                     taskId, Merge.SelectedMergeTarget ?? "", autostash: true);
@@ -1306,7 +1308,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             if (result?.Status == "dirty_target" && Dialogs != null)
                 await Dialogs.ShowErrorAsync(result.ErrorMessage ?? Loc.T("vm.detailsIsland.dirtyTarget"));
             else if (!hasChildren && result?.Status == "conflict")
-                await _merge.ResolveConflictAsync(taskId, Merge.SelectedMergeTarget ?? "");
+                await _merge.ResolveConflictAsync(taskId, Merge.SelectedMergeTarget ?? "", stashed);
             // The merge itself already landed; the verify command failed, so the task stayed
             // out of Done. Surface that instead of silently looking like nothing happened.
             else if (!hasChildren && result?.Status == "verify_failed" && Dialogs != null)