feat: 配置列表分页与钉钉机器人分钟级排队限流

统一 sources/templates/channels/rules 列表为分页响应，避免配置增多时全量返回；按钉钉 access_token 限制每分钟发送并在超限时等待下一分钟，降低触发官方封禁风险。

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/store/channel.go

@@ -47,10 +47,16 @@ func (s *Store) GetChannelByName(ctx context.Context, name string) (*model.Chann
 	return &ch, nil
 }
 
-func (s *Store) ListChannels(ctx context.Context) ([]model.Channel, error) {
-	rows, err := s.DB.QueryContext(ctx, `SELECT id, name, type, config, status, created_at, updated_at FROM notification_channel ORDER BY id`)
+func (s *Store) ListChannels(ctx context.Context, page PageFilter) ([]model.Channel, int, error) {
+	var count int
+	if err := s.DB.GetContext(ctx, &count, `SELECT COUNT(*) FROM notification_channel`); err != nil {
+		return nil, 0, fmt.Errorf("count channels: %w", err)
+	}
+
+	page.Normalize()
+	rows, err := s.DB.QueryContext(ctx, `SELECT id, name, type, config, status, created_at, updated_at FROM notification_channel ORDER BY id LIMIT ? OFFSET ?`, page.PageSize, page.Offset())
 	if err != nil {
-		return nil, fmt.Errorf("list channels: %w", err)
+		return nil, 0, fmt.Errorf("list channels: %w", err)
 	}
 	defer rows.Close()
 
@@ -59,13 +65,13 @@ func (s *Store) ListChannels(ctx context.Context) ([]model.Channel, error) {
 		var ch model.Channel
 		var configBytes []byte
 		if err := rows.Scan(&ch.ID, &ch.Name, &ch.Type, &configBytes, &ch.Status, &ch.CreatedAt, &ch.UpdatedAt); err != nil {
-			return nil, fmt.Errorf("scan channel: %w", err)
+			return nil, 0, fmt.Errorf("scan channel: %w", err)
 		}
 		raw := json.RawMessage(configBytes)
 		ch.Config = &raw
 		channels = append(channels, ch)
 	}
-	return channels, rows.Err()
+	return channels, count, rows.Err()
 }
 
 func (s *Store) UpdateChannel(ctx context.Context, id int, ch *model.Channel) error {