feat(worker): add WorktreeMaintenanceService for idle-worktree cleanup

src/ClaudeDo.Data/Repositories/WorktreeRepository.cs

@@ -40,4 +40,17 @@ public sealed class WorktreeRepository
     {
         await _context.Worktrees.Where(w => w.TaskId == taskId).ExecuteDeleteAsync(ct);
     }
+
+    public async Task<List<WorktreeEntity>> GetAllAsync(CancellationToken ct = default)
+    {
+        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);
+    }
 }