fix(worker-client): stop swallowing mutating hub call failures

TryInvokeAsync catches every exception and returns null, which is fine
for read-only calls but hid real HubException reasons behind a generic
"offline" message for the 7 mutating call sites (RestoreDefaultAgents,
UpsertPrimeSchedule, AddDailyNote, CleanupFinishedWorktrees,
ResetAllWorktrees, ForceRemoveWorktree, BuildPlanningIntegrationBranch)
— the same bug class fixed for ApproveReview in e1807fd. Each of the 22
TryInvokeAsync call sites was audited; the 15 read-only ones are left
unchanged (empty/offline is the right display). For the 7 switched to
a direct hub invoke, every caller was checked and, where it had no
catch, one was added so the exception surfaces (StatusMessage,
ShowErrorAsync/CombinedWarning) instead of crashing.

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

@@ -27,6 +27,33 @@ public class NotesEditorViewModelTests
         public Task DeleteAsync(string id) { Store.RemoveAll(n => n.Id == id); return Task.CompletedTask; }
     }
 
+    private sealed class ThrowingNotes : INotesApi
+    {
+        public string ExceptionMessage { get; init; } = "worker offline";
+        public Task<List<DailyNoteDto>> ListAsync(DateOnly day) => Task.FromResult(new List<DailyNoteDto>());
+        public Task<DailyNoteDto?> AddAsync(DateOnly day, string text) => throw new Exception(ExceptionMessage);
+        public Task UpdateAsync(string id, string text) => Task.CompletedTask;
+        public Task DeleteAsync(string id) => Task.CompletedTask;
+    }
+
+    [Fact]
+    public async Task AddBullet_WhenApiThrows_RaisesErrorReported_AndKeepsDraftText()
+    {
+        var api = new ThrowingNotes();
+        var vm = new NotesEditorViewModel(api);
+        await vm.LoadDayAsync(new DateOnly(2026, 6, 1));
+
+        string? reportedError = null;
+        vm.ErrorReported += msg => reportedError = msg;
+
+        vm.NewBulletText = "Standup vorbereitet";
+        await vm.AddBulletCommand.ExecuteAsync(null);
+
+        Assert.Equal(api.ExceptionMessage, reportedError);
+        Assert.Empty(vm.Bullets);
+        Assert.Equal("Standup vorbereitet", vm.NewBulletText);
+    }
+
     [Fact]
     public async Task AddBullet_PersistsAndAppears_ForCurrentDay()
     {