迁移上游子智能体功能线：ChatGroup 分组体系 + subagent_model 配置 + spawn 会话归属

- chats/models.py: SessionSource.subagent + ChatGroupKind/ChatGroup/default_chat_groups + ChatSpec 扩展 group_id/parent_session_id/root_session_id/last_finished_at + ChatsFile.groups
- chats/manager.py: group CRUD 方法(list/create/update/reorder/delete) + get_or_create_chat/create_chat 的 group 归属与校验
- chats/api.py: /chats/groups 端点(GET/POST/PUT order/PUT/DELETE)
- config.py+agents.py: AgentConfig.subagent_model 配置
- agent_management.py: _build_subagent_request_context 补 subagent_model→model_slot_override
- console.py: _chat_registration_fields 识别 spawn_subagent 请求并注册 subagent 会话
- constant.py: DEFAULT_SPAWN_FOREGROUND_TIMEOUT_SECONDS
- 前端 chat.ts: groups API 请求函数

console/src/api/modules/chat.ts

@@ -7,6 +7,7 @@ import type {
   ChatDeleteResponse,
   ChatUpdateRequest,
   BatchArchiveResult,
+  ChatGroup,
   Session,
 } from "../types";
 
@@ -126,6 +127,32 @@ export const chatApi = {
     request<void>(`/console/chat/stop?chat_id=${encodeURIComponent(chatId)}`, {
       method: "POST",
     }),
+
+  listGroups: () => request<ChatGroup[]>("/chats/groups"),
+
+  createGroup: (name: string) =>
+    request<ChatGroup>("/chats/groups", {
+      method: "POST",
+      body: JSON.stringify({ name }),
+    }),
+
+  updateGroup: (groupId: string, update: { name?: string; pinned?: boolean }) =>
+    request<ChatGroup>(`/chats/groups/${encodeURIComponent(groupId)}`, {
+      method: "PUT",
+      body: JSON.stringify(update),
+    }),
+
+  reorderGroups: (groupIds: string[]) =>
+    request<ChatGroup[]>("/chats/groups/order", {
+      method: "PUT",
+      body: JSON.stringify({ group_ids: groupIds }),
+    }),
+
+  deleteGroup: (groupId: string) =>
+    request<{ success: boolean; group_id: string }>(
+      `/chats/groups/${encodeURIComponent(groupId)}`,
+      { method: "DELETE" },
+    ),
 };
 
 export const sessionApi = {