docs: 更新 L1A 增量功能说明及 ETL 文档

ETL/L1A.py

@@ -1,4 +1,16 @@
+"""
+L1A Data Ingestion Script
+
+This script reads raw JSON files from the 'output_arena' directory and ingests them into the SQLite database.
+It supports incremental updates by default, skipping files that have already been processed.
+
+Usage:
+    python ETL/L1A.py           # Standard incremental run
+    python ETL/L1A.py --force   # Force re-process all files (overwrite existing data)
+"""
+
 import os
+
 import json
 import sqlite3
 import glob