console: 任务详情自动显示成本明细

打开详情就自动拉 GET /tasks/{id}/cost（不再只靠
“查成本”按钮出 JSON），详情顶部新一行：美元、总
token（实际/估算、缓存、无价单列）、轮数、fallback
次数；美元小于 1 美分时用 4 位小数，避免小任务
显示成 $0.00 误导成免费；加载中/失败有各自的
弱化文案，成本拉失败不影响详情其它内容；原
“查成本”按钮不动，仍可手动拉原始 JSON。
服务端不用改：成本接口与 _get_task 的 token 聚合
都已在 #150 / 详情 meta 那单里就位。

cloud/console-react/src/context.ts

@@ -1,5 +1,5 @@
 import { createContext, useContext } from "react";
-import type { Automation, Env, Member, Project, Review, Approval, Followup, PeerMessage, Task, ThreadInfo, Triage, Worker, SkillItem, McpServer, Agent, DispatchBody, ReviewBody, TraceEntry, ChatHistory } from "./api/types";
+import type { Automation, Env, Member, Project, Review, Approval, Followup, PeerMessage, Task, TaskCost, ThreadInfo, Triage, Worker, SkillItem, McpServer, Agent, DispatchBody, ReviewBody, TraceEntry, ChatHistory } from "./api/types";
 
 export interface ConsoleCtx {
   keySaved: boolean; keyState: string;
@@ -23,7 +23,7 @@ export interface ConsoleCtx {
   statusFilter: string; setStatusFilter: (v: string) => void; executorFilter: string; setExecutorFilter: (v: string) => void; searchText: string; setSearchText: (v: string) => void;
   filteredTasks: Task[];
   currentTask: Task | null; detailBody: string; actionMsg: string; actionReasons: string;
-  showDetail: (id: string) => void; doAction: (kind: string) => void; taskCost: () => void; costBox: string;
+  showDetail: (id: string) => void; doAction: (kind: string) => void; taskCost: () => void; costBox: string; costSummary: TaskCost | null | undefined;
   forkVisible: boolean; setForkVisible: (v: boolean) => void; forkTask: (msg: string) => Promise<void>; forkMsg: string;
   // Continue input is ContinuePanel (ChatInput); its send path is sendChatMessage below.
   coordChildren: Task[]; coordText: string; agents: Agent[]; agentsNote: string;