增加模型选择功能，支持不同 Agent 模型

src/components/chat/GlobalChatbox.tsx

@@ -3,6 +3,7 @@
 import React, { useCallback, useEffect, useRef, useState } from "react";
 import { Box, Drawer, alpha, useTheme } from "@mui/material";
 
+import type { AgentModel } from "@/lib/chatStream";
 import { AgentComposer } from "./AgentComposer";
 import { AgentHeader } from "./AgentHeader";
 import { AgentHistoryPanel } from "./AgentHistoryPanel";
@@ -19,6 +20,9 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
   const [width, setWidth] = useState(520);
   const [isResizing, setIsResizing] = useState(false);
   const [isHistoryOpen, setIsHistoryOpen] = useState(false);
+  const [selectedModel, setSelectedModel] = useState<AgentModel>(
+    "deepseek/deepseek-v4-pro",
+  );
 
   const bottomRef = useRef<HTMLDivElement>(null);
   const inputRef = useRef<HTMLInputElement | null>(null);
@@ -65,6 +69,7 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
   } = useAgentChatSession({
     onToolCall: handleToolCall,
     onBeforeSend: stopListening,
+    getModel: () => selectedModel,
   });
 
   useEffect(() => {
@@ -298,6 +303,8 @@ export const GlobalChatbox: React.FC<Props> = ({ open, onClose }) => {
               onStartListening={startListening}
               onStopListening={stopListening}
               onPresetSelect={handlePresetPromptSelect}
+              selectedModel={selectedModel}
+              onModelChange={setSelectedModel}
             />
           </Box>
         </Box>