fix: 自动化开始前清除旧透传记录，重置所有计数和显示

edc-web/app/models.py

@@ -108,6 +108,17 @@ def get_serialnet_records(dnt_id: int, limit: int = 50) -> list[dict]:
         conn.close()
 
 
+def clear_serialnet_records(dnt_id: int):
+    """清除指定设备的所有透传记录"""
+    conn = get_conn()
+    try:
+        with conn.cursor() as cur:
+            cur.execute("DELETE FROM tb_serialnet WHERE dnt_id=%s", (dnt_id,))
+        conn.commit()
+    finally:
+        conn.close()
+
+
 # ─── tb_state_tst ──────────────────────────────────────────────────
 
 def get_latest_test_state(dnt_id: int) -> dict | None: