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/pkb/controllers/documentController.ts

@@ -1,8 +1,16 @@
 import type { FastifyRequest, FastifyReply } from 'fastify';
 import * as documentService from '../services/documentService.js';
 
-// Mock用户ID（实际应从JWT token中获取）
-const MOCK_USER_ID = 'user-mock-001';
+/**
+ * 获取用户ID（从JWT Token中获取）
+ */
+function getUserId(request: FastifyRequest): string {
+  const userId = (request as any).user?.userId;
+  if (!userId) {
+    throw new Error('User not authenticated');
+  }
+  return userId;
+}
 
 /**
  * 上传文档
@@ -69,8 +77,9 @@ export async function uploadDocument(
 
     // 上传文档（这里fileUrl暂时为空，实际应该上传到对象存储）
     console.log(`⚙️ 调用文档服务上传文件...`);
+    const userId = getUserId(request);
     const document = await documentService.uploadDocument(
-      MOCK_USER_ID,
+      userId,
       kbId,
       file,
       filename,
@@ -123,7 +132,8 @@ export async function getDocuments(
   try {
     const { kbId } = request.params;
 
-    const documents = await documentService.getDocuments(MOCK_USER_ID, kbId);
+    const userId = getUserId(request);
+    const documents = await documentService.getDocuments(userId, kbId);
 
     return reply.send({
       success: true,
@@ -160,7 +170,8 @@ export async function getDocumentById(
   try {
     const { id } = request.params;
 
-    const document = await documentService.getDocumentById(MOCK_USER_ID, id);
+    const userId = getUserId(request);
+    const document = await documentService.getDocumentById(userId, id);
 
     return reply.send({
       success: true,
@@ -197,7 +208,8 @@ export async function deleteDocument(
   try {
     const { id } = request.params;
 
-    await documentService.deleteDocument(MOCK_USER_ID, id);
+    const userId = getUserId(request);
+    await documentService.deleteDocument(userId, id);
 
     return reply.send({
       success: true,
@@ -234,7 +246,8 @@ export async function reprocessDocument(
   try {
     const { id } = request.params;
 
-    await documentService.reprocessDocument(MOCK_USER_ID, id);
+    const userId = getUserId(request);
+    await documentService.reprocessDocument(userId, id);
 
     return reply.send({
       success: true,
@@ -271,7 +284,8 @@ export async function getDocumentFullText(
   try {
     const { id } = request.params;
 
-    const document = await documentService.getDocumentById(MOCK_USER_ID, id);
+    const userId = getUserId(request);
+    const document = await documentService.getDocumentById(userId, id);
 
     // 返回完整的文档信息
     return reply.send({