feat(ui): notes mode in the Details island

Add IsNotesMode/Notes to DetailsIslandViewModel; ShowNotes() loads today's
notes and switches the island body to NotesEditorView via IsVisible toggling.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.App/Program.cs

@@ -126,7 +126,8 @@ sealed class Program
             new DetailsIslandViewModel(
                 sp.GetRequiredService<IDbContextFactory<ClaudeDoDbContext>>(),
                 sp.GetRequiredService<WorkerClient>(),
-                sp));
+                sp,
+                sp.GetRequiredService<INotesApi>()));
         sc.AddSingleton<IslandsShellViewModel>();
 
         return sc.BuildServiceProvider();