[RAG] PDF阅读模式改用pdfplumber(文本+表格提取，干净HTML)；修复ck_mysql_config导入

langchain-chat/server/knowledge_base/kb_doc_api.py

@@ -4,9 +4,10 @@ import urllib
 from fastapi import File, Form, Body, Query, Response, UploadFile
 from configs import (DEFAULT_VS_TYPE, EMBEDDING_MODEL,
                      VECTOR_SEARCH_TOP_K, SCORE_THRESHOLD,
-                     EXPR, 
+                     EXPR,
                      CHUNK_SIZE, OVERLAP_SIZE, ZH_TITLE_ENHANCE,
                      logger, log_verbose, POLICY_KNOWLEDGE_BASE)
+from configs.kb_config import ck_mysql_config
 from configs.model_config import LLM_MODELS
 from server.knowledge_base.cleanpdf import PdfConverter
 from server.knowledge_base.file_converter import FileConverter