feat(etl): 实现批次编排与 CLI 入口，支持 --max-batches 冒烟测试参数

+#!/usr/bin/env python3
+import argparse
+from etl_to_crawler.config import PLATFORM_QQ, PLATFORM_KUGOU, PLATFORM_NETEASE, PLATFORMS
+from etl_to_crawler.runner import run
+
+PLATFORM_MAP = {
+    'qq': PLATFORM_QQ,
+    'kugou': PLATFORM_KUGOU,
+    'netease': PLATFORM_NETEASE,
+}
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='ETL: hk_songs_test → crawler_dev')
+    parser.add_argument('--platform', default='all',
+                        choices=['qq', 'kugou', 'netease', 'all'],
+                        help='要导入的平台（默认 all）')
+    parser.add_argument('--max-batches', type=int, default=None,
+                        help='最多处理多少批次（冒烟测试用）')
+    args = parser.parse_args()
+
+    if args.platform == 'all':
+        platforms = PLATFORMS
+    else:
+        platforms = [PLATFORM_MAP[args.platform]]
+
+    print(f"Starting ETL for platforms: {platforms}")
+    run(platforms, max_batches=args.max_batches)