fix: import os ordering

wwwroot/api/workspace_browse.dspy

@@ -6,6 +6,7 @@ if not uid:
 
 dbname = get_module_dbname('pipeline-sdlc')
 workspace_base = '/d/pipeline/workspaces'
+import os
 
 async with DBPools().sqlorContext(dbname) as sor:
     recs = await sor.sqlExe(
@@ -30,7 +31,6 @@ async with DBPools().sqlorContext(dbname) as sor:
 if not ws_dir or not os.path.isdir(ws_dir):
     return json.dumps({"error": "工作空间不存在: " + ws_dir, "tree": {"name": "", "children": [], "files": []}}, ensure_ascii=False)
 
-import os
 
 def build_tree(path):
     result = {"name": os.path.basename(path) or path, "path": path, "children": [], "files": []}