feat(web): 添加全局 Toast 通知系统和资产预览导航功能

- 新增 ToastProvider 和 useToast hook，支持全局成功/错误/信息提示
- 资产预览增加左右导航按钮、键盘快捷键(方向键)和计数器显示
- 资产库增加图片/视频类型筛选标签页及计数
- 对话列表增加最近对话展示、搜索优化和删除确认
- 消息增加删除确认对话框
- 优化聊天自动滚动行为，仅在用户未手动滚动时跟随新内容
- 新增删除消息 API 端点
- 优化消息历史清理逻辑，过滤错误消息和孤儿 tool 消息
- 添加自定义滚动条样式
- 优化账户参考图显示逻辑，支持本地文件显示
- 修复对话创建流程，直接导航到新创建的对话

web/client/src/hooks/useChat.ts

@@ -16,10 +16,13 @@ export function useChat(conversationId: string | null) {
   const [thinking, setThinking] = useState(false);
   const [toolStatus, setToolStatus] = useState<string | null>(null);
   const [pipeline, setPipeline] = useState<PipelineState | null>(null);
-  const initRef = useRef(false);
+
+  // Track which conversation is currently loaded via WS
+  const activeConvRef = useRef<string | null>(null);
+  // Pending conversation creation resolve
+  const createResolveRef = useRef<((id: string) => void) | null>(null);
 
   useEffect(() => {
-    // Bind all event handlers once
     const onConnected = () => setConnected(true);
     const onHistory = (data: Record<string, unknown>) => {
       setMessages((data.messages as Message[]) || []);
@@ -82,6 +85,14 @@ export function useChat(conversationId: string | null) {
         status: data.status as string | undefined,
       });
     };
+    const onConversationCreated = (data: Record<string, unknown>) => {
+      const id = data.id as string;
+      activeConvRef.current = id;
+      if (createResolveRef.current) {
+        createResolveRef.current(id);
+        createResolveRef.current = null;
+      }
+    };
 
     chatSocket.on('connected', onConnected);
     chatSocket.on('history', onHistory);
@@ -95,6 +106,7 @@ export function useChat(conversationId: string | null) {
     chatSocket.on('tool_result', onToolResult);
     chatSocket.on('tool_error', onToolError);
     chatSocket.on('pipeline_progress', onPipelineProgress);
+    chatSocket.on('conversation_created', onConversationCreated);
     chatSocket.connect();
 
     return () => {
@@ -110,19 +122,30 @@ export function useChat(conversationId: string | null) {
       chatSocket.off('tool_result', onToolResult);
       chatSocket.off('tool_error', onToolError);
       chatSocket.off('pipeline_progress', onPipelineProgress);
+      chatSocket.off('conversation_created', onConversationCreated);
       chatSocket.disconnect();
     };
   }, []);
 
-  // Load conversation when ID changes
+  // Init/re-init when conversationId changes
   useEffect(() => {
-    if (conversationId && connected && !initRef.current) {
-      initRef.current = true;
+    if (!connected) return;
+
+    if (conversationId && conversationId !== activeConvRef.current) {
+      activeConvRef.current = conversationId;
+      setMessages([]);
+      setThinking(false);
+      setToolStatus(null);
+      setPipeline(null);
       chatSocket.send('init', { conversationId });
     }
+
     if (!conversationId) {
-      initRef.current = false;
+      activeConvRef.current = null;
       setMessages([]);
+      setThinking(false);
+      setToolStatus(null);
+      setPipeline(null);
     }
   }, [conversationId, connected]);
 
@@ -134,12 +157,23 @@ export function useChat(conversationId: string | null) {
     chatSocket.stop();
   }, []);
 
-  const createConversation = useCallback((title: string, accountId?: string) => {
-    chatSocket.send('create_conversation', { title, accountId });
+  const createConversation = useCallback((title: string, accountId?: string): Promise<string> => {
+    return new Promise((resolve) => {
+      createResolveRef.current = resolve;
+      chatSocket.send('create_conversation', { title, accountId });
+      // Timeout fallback
+      setTimeout(() => {
+        if (createResolveRef.current) {
+          createResolveRef.current = null;
+          resolve('');
+        }
+      }, 5000);
+    });
   }, []);
 
-  const removeMessage = useCallback((msgId: string) => {
+  const removeMessage = useCallback(async (msgId: string) => {
     setMessages((prev) => prev.filter((m) => m.id !== msgId));
+    try { await fetch(`/api/pipeline/messages/${msgId}`, { method: 'DELETE' }); } catch {}
   }, []);
 
   return { messages, connected, thinking, toolStatus, pipeline, send, stop, createConversation, removeMessage };