feat: replace pymupdf image extraction with pdf2image + Heron layout detection

PDF image extraction now renders pages with pdf2image, detects figure
regions using docling-layout-heron (RT-DETRv2), and crops only the
detected pictures. Removes full-page fallback for text-only pages.

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

web/src/app/(main)/knowledge/[id]/page.tsx

@@ -33,7 +33,7 @@ import {
   Settings
 } from "lucide-react";
 import { formatFileSize, formatDate } from "@/lib/utils";
-import { knowledgeBaseAPI } from "@/lib/api";
+import { knowledgeBaseAPI, resolveImageUrl } from "@/lib/api";
 import { KnowledgeBaseDetail, Document } from "@/types";
 
 export default function KnowledgeBaseDetailPage() {
@@ -158,13 +158,12 @@ export default function KnowledgeBaseDetailPage() {
   const handleViewDocument = async (doc: Document) => {
     try {
       const token = localStorage.getItem("auth_token");
-      const res = await fetch(`/api/knowledge-bases/documents/${doc.id}/download`, {
+      const res = await fetch(resolveImageUrl(`/knowledge-bases/documents/${doc.id}/download`), {
         headers: { Authorization: `Bearer ${token}` },
       });
-      if (!res.ok) throw new Error("下载失败");
+      if (!res.ok) throw new Error("获取文档失败");
       const blob = await res.blob();
 
-      // 从 Content-Disposition 提取文件名，或用 doc 信息拼接
       const disposition = res.headers.get("Content-Disposition");
       let filename = `${doc.title}${doc.file_type}`;
       if (disposition) {
@@ -172,15 +171,11 @@ export default function KnowledgeBaseDetailPage() {
         if (match) filename = decodeURIComponent(match[1].replace(/["']/g, ""));
       }
 
-      // 触发浏览器下载
       const url = URL.createObjectURL(blob);
-      const a = document.createElement("a");
-      a.href = url;
-      a.download = filename;
-      a.click();
-      URL.revokeObjectURL(url);
+      window.open(url, '_blank');
+      setTimeout(() => URL.revokeObjectURL(url), 60000);
     } catch {
-      window.open(`/api/knowledge-bases/documents/${doc.id}/download`, '_blank');
+      window.open(resolveImageUrl(`/knowledge-bases/documents/${doc.id}/download`), '_blank');
     }
   };
 

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

@@ -113,7 +113,18 @@ export default function MessageItem({ message, selectedModel }: MessageItemProps
 
   const handleCopy = async () => {
     try {
-      await navigator.clipboard.writeText(message.content);
+      if (navigator.clipboard && window.isSecureContext) {
+        await navigator.clipboard.writeText(message.content);
+      } else {
+        const textarea = document.createElement("textarea");
+        textarea.value = message.content;
+        textarea.style.position = "fixed";
+        textarea.style.left = "-9999px";
+        document.body.appendChild(textarea);
+        textarea.select();
+        document.execCommand("copy");
+        document.body.removeChild(textarea);
+      }
       toast.success("已复制");
     } catch {
       toast.error("复制失败");

web/src/store/chat.ts

@@ -339,6 +339,15 @@ export const useChatStore = create<ChatStore>((set, get) => ({
           scheduleFlush();
         },
         (_sessionId: number, messageId?: number, userMessageId?: number) => {
+          // 刷出缓冲区中剩余的内容
+          if (rafId !== null) {
+            cancelAnimationFrame(rafId);
+            rafId = null;
+          }
+          if (contentBuffer) {
+            flushBuffer();
+          }
+
           if (messageId) {
             set((state) => ({
               messages: state.messages.map(msg => {