refactor(data/exchanges): 多子类架构 + 工厂入口

- 每个交易所独立子类：BinanceRestClient extends BaseRestClient
- 统一入口 createRestClient(exchangeId) 工厂函数
- KLINE_INTERVAL_MS 移至 constants.ts
- fetchKlines 签名统一为 (symbol, startTime, limit?, endTime?)
- throttle 限流实际生效
- convertBinanceKline interval 参数化
- 删除 filterConsecutive 死代码
- 更新 run/exchange.ts 和 service/bnkline.ts 调用方

data/exchanges/index.ts

@@ -0,0 +1,32 @@
+import { BaseRestClient } from "./base";
+import { BinanceRestClient } from "./binance/rest";
+
+/** 交易所 ID 到 RestClient 构造器的注册表 */
+const registry: Record<string, () => BaseRestClient> = {
+    binance: () => new BinanceRestClient(),
+};
+
+/**
+ * 创建交易所 REST 客户端。
+ *
+ * 根据交易所 ID 返回对应的 RestClient 实例，
+ * 外部无需感知具体子类。
+ *
+ * @param exchangeId - 交易所标识（如 "binance"）
+ * @returns 对应交易所的 RestClient 实例
+ * @throws 如果 exchangeId 未注册
+ */
+export function createRestClient(exchangeId: string): BaseRestClient {
+    const factory = registry[exchangeId];
+    if (!factory) {
+        const supported = Object.keys(registry).join(", ");
+        throw new Error(
+            `[exchanges] 不支持的交易所: "${exchangeId}"，当前支持: ${supported}`,
+        );
+    }
+    return factory();
+}
+
+export { BaseRestClient } from "./base";
+export { BinanceRestClient } from "./binance/rest";
+export { KLINE_INTERVAL_MS } from "./constants";