feat: system knowledge base management with admin/user role separation

- Auto-create system KBs from data/knowledge_base/ subdirectories on startup
- Upgrade existing user KBs to system KBs when matching directory found
- Admin can upload to system KBs (saved to knowledge_base dir)
- Regular users see only their own KBs on knowledge page
- Fix API permission checks for system KBs (list, detail, documents, update, delete)
- Add is_superuser to UserResponse and frontend User type
- Fix sidebar session menu visibility for long titles

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/src/components/chat/export-dialog.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { useState } from "react";
-import { Download, FileText, FileJson, File } from "lucide-react";
+import { Download, FileText, FileJson } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import {
   Dialog,
@@ -61,12 +61,6 @@ export default function ExportDialog({ sessionId, sessionTitle, children, onClos
       description: "可读性好的文本格式，适合分享",
       icon: FileText,
     },
-    {
-      value: "pdf",
-      label: "PDF 格式",
-      description: "适合打印和正式文档",
-      icon: File,
-    },
   ];
 
   return (

web/src/components/chat/message-item.tsx

@@ -11,7 +11,7 @@ import { format } from "date-fns";
 import { Button } from "@/components/ui/button";
 import { useChatStore } from "@/store/chat";
 import SourceReferences from "./source-references";
-import { useState } from "react";
+import { useState, useEffect } from "react";
 import { toast } from "sonner";
 
 interface MessageItemProps {
@@ -21,6 +21,7 @@ interface MessageItemProps {
 
 const ThinkingProcess = ({ thinking, isStreaming }: { thinking: ThinkingStep[]; isStreaming?: boolean }) => {
   const [expanded, setExpanded] = useState(false);
+
   if (!thinking || thinking.length === 0) return null;
 
   // 只提取有实际内容的步骤：推理内容和检索文档
@@ -32,6 +33,11 @@ const ThinkingProcess = ({ thinking, isStreaming }: { thinking: ThinkingStep[];
   // 没有推理内容也没有文档详情时不显示
   if (!hasReasoning && !hasDocs && !isStreaming) return null;
 
+  // 流式生成时自动展开，完成后自动收起
+  useEffect(() => {
+    setExpanded(!!isStreaming);
+  }, [isStreaming]);
+
   // 合并推理文本
   const reasoningText = reasoningSteps.map(s => s.message).join('');
 

web/src/components/chat/sidebar.tsx

@@ -13,6 +13,7 @@ import {
   Download,
   Search,
   MoreVertical,
+  PanelLeftClose,
 } from "lucide-react";
 import {
   DropdownMenu,
@@ -121,9 +122,13 @@ export default function Sidebar({ onClose }: SidebarProps) {
       <div className="px-3 pt-4 pb-3 space-y-3 border-b border-border/30">
         <div className="flex items-center justify-between px-1">
           <span className="text-sm font-semibold text-foreground">对话</span>
-          <Button onClick={handleNewChat} size="sm" variant="ghost" className="h-7 w-7 p-0 hover:bg-primary/10 hover:text-primary">
-            <Plus className="w-4 h-4" />
-          </Button>
+          <button
+            onClick={onClose}
+            className="h-7 w-7 flex items-center justify-center rounded-md text-muted-foreground hover:text-foreground hover:bg-muted/50 transition-colors"
+            title="收起侧边栏"
+          >
+            <PanelLeftClose className="w-4 h-4" />
+          </button>
         </div>
         <div className="relative">
           <Search className="absolute left-2.5 top-1/2 -translate-y-1/2 w-3.5 h-3.5 text-muted-foreground" />