use sys.argv[1] for Pipeline initialization

csst_common/pipeline.py

@@ -12,6 +12,7 @@ Modified-History:
     2025-12-27, Bo Zhang, rewrite Pipeline class
 """
 
+import sys
 import json
 import subprocess
 import os
@@ -64,12 +65,12 @@ class Pipeline:
     {'a': 1}
     """
 
-    def __init__(self, msg: str = "", **env_vars: Any):
+    def __init__(self, **env_vars: Any):
         # record start time
         self.t_start = Time.now()
 
         # set message
-        self.msg = msg
+        self.msg = sys.argv[1]
         self.msg_dict = self.json2dict(self.msg)
 
         # set environment variables