feat: 用自定义侧边栏替换聊天室 Conversations 组件，提取公共 SidebarGroup 和 date-group

src/web/shared/components/SidebarGroup/index.tsx

@@ -0,0 +1,28 @@
+import { CaretDownOutlined, CaretRightOutlined } from "@ant-design/icons";
+import { Typography } from "antd";
+import { type ReactNode, useState } from "react";
+
+interface SidebarGroupProps {
+  children: ReactNode;
+  count: number;
+  label: string;
+}
+
+export function SidebarGroup({ children, count, label }: SidebarGroupProps) {
+  const [collapsed, setCollapsed] = useState(false);
+
+  return (
+    <div className="app-sidebar-group">
+      <div className="app-sidebar-group-header" onClick={() => setCollapsed(!collapsed)}>
+        <span className="app-sidebar-group-arrow">{collapsed ? <CaretRightOutlined /> : <CaretDownOutlined />}</span>
+        <Typography.Text className="app-sidebar-group-label" type="secondary">
+          {label}
+        </Typography.Text>
+        <Typography.Text className="app-sidebar-group-count" type="secondary">
+          ({count})
+        </Typography.Text>
+      </div>
+      {!collapsed && <div className="app-sidebar-group-content">{children}</div>}
+    </div>
+  );
+}