fix(ai): 自動偵測挑品銷售欄位

tests/test_frontend_v2_assets.py

@@ -148,7 +148,9 @@ def test_ai_product_pick_agent_uses_real_competitor_data_and_dashboard_action():
     assert "'product_pick'" in agent_source
     assert "PChomeProductPickAgent" in agent_source
     assert "PChome 價格優勢" in agent_source
-    assert "snapshot_date::date" in agent_source
+    assert "_daily_sales_columns" in agent_source
+    assert '"總業績"' in agent_source
+    assert "{date_col}::date" in agent_source
     assert "conn.rollback()" in agent_source
 
     assert "@ai_bp.route('/api/ai/product-picks/generate', methods=['POST'])" in route_source