refactor(global_var): 重构全局变量管理

- 移除了 _docs 全局变量
- 更新了 get_docs() 函数，使其在每次调用时重新扫描文档目录
- 优化了全局变量初始化逻辑

global_var.py

@@ -3,16 +3,14 @@ from tools import scan_docs_directory
 
 _prompt_store = None
 _sql_engine = None
-_docs = None
 _datasets = None
 _model = None
 _tokenizer = None
 _workdir = None
 def init_global_var(workdir="workdir"):
-    global _prompt_store, _sql_engine, _docs, _datasets, _workdir
+    global _prompt_store, _sql_engine, _datasets, _workdir
     _prompt_store = get_prompt_tinydb(workdir)
     _sql_engine = get_sqlite_engine(workdir)
-    _docs = scan_docs_directory(workdir)
     _datasets = get_all_dataset(workdir)
     _workdir = workdir
 
@@ -34,12 +32,8 @@ def set_sql_engine(new_sql_engine):
     _sql_engine = new_sql_engine
 
 def get_docs():
-    return _docs
-
-def set_docs(new_docs):
-    global _docs
-    _docs = new_docs
-
+    global _workdir
+    return scan_docs_directory(_workdir)
 def get_datasets():
     return _datasets