fix: 使用 Portal 渲染标签预览弹窗到 body，修复 backdrop-blur 导致 fixed 定位失效的问题

components/canvas/CanvasChatPanel.tsx

@@ -3,6 +3,7 @@
 import { useChat } from "@ai-sdk/react";
 import { DefaultChatTransport } from "ai";
 import { useEffect, useRef, useState, useCallback } from "react";
+import { createPortal } from "react-dom";
 import { useRouter } from "next/navigation";
 import useSWR from "swr";
 import { Send, Loader2, ImagePlus, Paperclip, X, Sparkles, User, Bot, Plus, History, Share2, LayoutGrid, Maximize2, RefreshCw, Zap, Globe, Box, ArrowUp } from "lucide-react";
@@ -1483,7 +1484,8 @@ export function CanvasChatPanel({ chatId, initialMessages = [], onClose, onOpenF
           top = padding;
         }
         
-        return (
+        // 使用 Portal 渲染到 body，避免 backdrop-blur 影响 fixed 定位
+        return createPortal(
           <div
             data-tag-preview="true"
             className="fixed z-[10001] bg-white dark:bg-zinc-900 rounded-xl shadow-2xl border border-border/50 overflow-hidden animate-in fade-in zoom-in-95 duration-150"
@@ -1560,7 +1562,8 @@ export function CanvasChatPanel({ chatId, initialMessages = [], onClose, onOpenF
                 </div>
               )}
             </div>
-          </div>
+          </div>,
+          document.body
         );
       })()}
     </div>