refactor: delete unreachable members and redundant package refs

Eight public members had no caller anywhere in src: GitService.GetFileDiffAsync,
SubtaskRepository.DeleteByTaskIdAsync, TaskRepository.GetByListAsync (a
backwards-compat alias for GetByListIdAsync) and .GetByCreatorAsync,
WorktreeRepository.GetByStatesAsync, TaskMonitorViewModel.SetPendingQuestion
(a duplicate of the live-event lambda), PrimeClaudeTabViewModel.ApplyFiredEvent,
and StreamLineFormatter.FormatFile. TaskAttachmentRepository.DeleteAllForTaskAsync
was reachable only from its own test; the ON DELETE CASCADE on task_attachments
already covers it. Tests for the deleted members go with them.

Dropped two package refs the platform already provides: EntityFrameworkCore.Design
in Worker (the design-time factory and the migrations live in Data, which has its
own ref) and System.IO.FileSystem.AccessControl in Installer.Tests (net8.0-windows
ships the ACL APIs in the shared framework).

src/ClaudeDo.Data/Repositories/WorktreeRepository.cs

@@ -65,12 +65,4 @@ public sealed class WorktreeRepository
     {
         return await _context.Worktrees.AsNoTracking().ToListAsync(ct);
     }
-
-    public async Task<List<WorktreeEntity>> GetByStatesAsync(
-        IReadOnlyCollection<WorktreeState> states, CancellationToken ct = default)
-    {
-        return await _context.Worktrees.AsNoTracking()
-            .Where(w => states.Contains(w.State))
-            .ToListAsync(ct);
-    }
 }