fix(merge): apply the verify gate to worktree-less approvals and report it everywhere

ApproveAndMergeAsync short-circuits to Done whenever a task has no active
worktree -- which is exactly how a list-handler task works, since it commits
straight into the list working dir. The verify command was skipped for the run
that lands the most on the target branch at once; the loaded command was even
discarded at the destructuring. It now runs under the same per-repo gate as the
merge path before the task may reach Done.

The two merge entry points that did not know verify_failed reported it as
"Unknown status: verify_failed" (merge modal, dropping the command output) and
as a generic Failed (worktrees batch, claiming the merge never happened).

src/ClaudeDo.Ui/ViewModels/Modals/MergeModalViewModel.cs

@@ -110,6 +110,12 @@ public sealed partial class MergeModalViewModel : ViewModelBase
                 case "blocked":
                     ErrorMessage = Loc.T("vm.merge.blocked", result.ErrorMessage ?? "");
                     break;
+                case "verify_failed":
+                    // The merge landed; only the Done transition was withheld. Deliberately not
+                    // treated as success -- no auto-close, because the failure text is the whole
+                    // point of the gate.
+                    ErrorMessage = result.ErrorMessage ?? Loc.T("vm.merge.verifyFailed");
+                    break;
                 default:
                     ErrorMessage = Loc.T("vm.merge.unknownStatus", result.Status);
                     break;