feat(ui): add MergeTaskAsync and GetMergeTargetsAsync to WorkerClient

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -179,6 +179,24 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable
         await _hub.InvokeAsync("ResetTask", taskId);
     }
 
+    public async Task<MergeResultDto> MergeTaskAsync(string taskId, string targetBranch, bool removeWorktree, string commitMessage)
+    {
+        return await _hub.InvokeAsync<MergeResultDto>(
+            "MergeTask", taskId, targetBranch, removeWorktree, commitMessage);
+    }
+
+    public async Task<MergeTargetsDto?> GetMergeTargetsAsync(string taskId)
+    {
+        try
+        {
+            return await _hub.InvokeAsync<MergeTargetsDto>("GetMergeTargets", taskId);
+        }
+        catch
+        {
+            return null;
+        }
+    }
+
     public async Task CancelTaskAsync(string taskId)
     {
         await _hub.InvokeAsync("CancelTask", taskId);
@@ -298,3 +316,5 @@ public sealed record AppSettingsDto(
 
 public sealed record WorktreeCleanupDto(int Removed);
 public sealed record WorktreeResetDto(int Removed, int TasksAffected, bool Blocked, int RunningTasks);
+public record MergeResultDto(string Status, IReadOnlyList<string> ConflictFiles, string? ErrorMessage);
+public record MergeTargetsDto(string DefaultBranch, IReadOnlyList<string> LocalBranches);