feat: impl dao (#1)

Co-authored-by: kould <2435992353@qq.com>

src/entity/mod.rs

@@ -0,0 +1,9 @@
+mod user_info;
+mod tag_info;
+mod tag_2_doc;
+mod kb_2_doc;
+mod dialog_2_kb;
+mod doc_2_doc;
+mod kb_info;
+mod doc_info;
+mod dialog_info;