fix(pkb): fix create KB and upload issues - remove simulated upload, fix department mapping, add upload modal

Fixed issues:
- Remove simulateUpload function from DashboardPage Step 3
- Map department to description field when creating KB
- Add upload modal in WorkspacePage knowledge assets tab
- Fix DocumentUpload import path (../../stores to ../stores)

Known issue: Dify API validation error during document upload (file uploaded but DB record failed, needs investigation)

Testing: KB creation works, upload dialog opens correctly

backend/src/modules/iit-manager/docs/微信服务号接入指南.md

@@ -540,3 +540,6 @@ URL: https://iit.xunzhengyixue.com/api/v1/iit/patient-wechat/callback
 
 
 
+
+
+