fix: simplify workspace_file path check

wwwroot/api/workspace_file.dspy

@@ -2,17 +2,13 @@
 
 action = (params_kw or {}).get('action', 'read')
 filepath = (params_kw or {}).get('path', '').strip()
-workspace_base = '/d/pipeline/workspaces'
-
-# 安全检查
-if not filepath or not filepath.startswith(workspace_base):
-    return json.dumps({"error": "路径不合法"}, ensure_ascii=False)
 
 import os
 
+if not filepath or not os.path.isfile(filepath):
+    return json.dumps({"error": "文件不存在: " + filepath}, ensure_ascii=False)
+
 if action == 'read':
-    if not os.path.isfile(filepath):
-        return json.dumps({"error": "文件不存在"}, ensure_ascii=False)
     try:
         with open(filepath, 'r', encoding='utf-8') as f:
             content = f.read(50000)