feat(ui): separate OperationStatus per worktree action (refresh/cleanup/reset/force-remove/batch-merge)

Replaces the shared IsBusy/IsMerging flags in WorktreesOverviewModalViewModel and the
reset flow in WorktreesSettingsTabViewModel with dedicated OperationStatus instances
shown via OperationIndicator, so a running Refresh no longer blocks the Cleanup
indicator. ForceRemove gains a CanExecute guard against re-entrancy while it's running,
and the reconcile tick's busy guard now checks all four action statuses instead of the
old IsBusy||IsMerging pair.

tests/ClaudeDo.Ui.Tests/ViewModels/WorktreesOverviewModalErrorTests.cs

@@ -20,6 +20,8 @@ public class WorktreesOverviewModalErrorTests
     private sealed class ThrowingWorker : StubWorkerClient
     {
         public string ExceptionMessage { get; init; } = "worktree is locked by another process";
+        public override Task<List<WorktreeOverviewDto>> GetWorktreesOverviewAsync(string? listId) =>
+            throw new Exception(ExceptionMessage);
         public override Task<WorktreeCleanupDto?> CleanupFinishedWorktreesAsync(string? listId = null) =>
             throw new Exception(ExceptionMessage);
         public override Task<ForceRemoveResultDto?> ForceRemoveWorktreeAsync(string taskId) =>
@@ -39,7 +41,7 @@ public class WorktreesOverviewModalErrorTests
 
         Assert.NotNull(vm.StatusMessage);
         Assert.Contains(worker.ExceptionMessage, vm.StatusMessage);
-        Assert.False(vm.IsBusy);
+        Assert.False(vm.CleanupStatus.IsRunning);
     }
 
     [Fact]
@@ -61,5 +63,17 @@ public class WorktreesOverviewModalErrorTests
         Assert.NotNull(vm.StatusMessage);
         Assert.Contains(worker.ExceptionMessage, vm.StatusMessage);
         Assert.Contains(row, vm.Rows);
+        Assert.False(vm.ForceRemoveStatus.IsRunning);
+    }
+
+    [Fact]
+    public async Task Refresh_WhenWorkerThrows_ResetsRefreshStatus()
+    {
+        var worker = new ThrowingWorker();
+        var vm = NewVm(worker);
+
+        await Assert.ThrowsAsync<Exception>(() => vm.RefreshCommand.ExecuteAsync(null));
+
+        Assert.False(vm.RefreshStatus.IsRunning);
     }
 }