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/TaskRepository.cs

@@ -84,10 +84,6 @@ public sealed class TaskRepository
         await _context.SaveChangesAsync(ct);
     }
 
-    // Kept for backwards-compatibility with callers using the old name.
-    public Task<List<TaskEntity>> GetByListAsync(string listId, CancellationToken ct = default)
-        => GetByListIdAsync(listId, ct);
-
     /// <summary>
     /// Returns the ids of every descendant of <paramref name="taskId"/> (children, grandchildren, ...),
     /// walking the ParentTaskId chain breadth-first. Does not include the task itself.
@@ -142,15 +138,6 @@ public sealed class TaskRepository
             .ExecuteUpdateAsync(s => s.SetProperty(t => t.SortOrder, (maxSort ?? -1) + 1), ct);
     }
 
-    public async Task<List<TaskEntity>> GetByCreatorAsync(string createdBy, CancellationToken ct = default)
-    {
-        return await _context.Tasks
-            .AsNoTracking()
-            .Where(t => t.CreatedBy == createdBy)
-            .OrderByDescending(t => t.CreatedAt)
-            .ToListAsync(ct);
-    }
-
     /// <summary>
     /// Returns all tasks that qualify as "real" Idle backlog items for online mirroring:
     /// Status==Idle, no parent, PlanningPhase==None, not blocked.