重构 worker 对话：复用 resume 机制，改专属 goroutine 运行

把「给运行中 Worker 发消息调方向」从自建的介入持久化协议，改为复用
已有的暂停/恢复 + transcript resume 能力，实现与主 Agent chat 一致。

- 拆 runWorkerStep：抽出 runIntent(执行+善后)，池子与消息路径共用一份
  善后逻辑；新增 runDetachedIntent，把意图 paused→running(不经 frontier)
  并在专属 goroutine 里直接跑，用户消息不受 3 槽池限制、随发随跑。
- 精简 sendWorkerMessage handler：校验 + emit 用户活动 + 专属运行；消息经
  ExecuteWithMessage 作为下一轮输入注入，request_id 仅做 transcript 去重。
- 删除介入 DB 协议与 15 处 activity 查询过滤(回退 exploration.go)、
  directedClaims 调度屏障、RecoverWorkerMessages 恢复、workerWake/waitWorker、
  AbortWorkIntervenedByUser。无 DB schema 改动。
- 前端：保留消息框，恢复「直接继续」(resume)按钮；发送改由 SSE 承载，
  去掉乐观插入。
- 取舍(低频可接受)：消息仅存内存，不做崩溃恢复；发消息时该任务可能瞬时
  超并发 1 个 worker。

净改动 9 文件 +583/-46(原 PR 15 文件 +1940/-72)。

web/src/lib/api.ts

@@ -287,9 +287,8 @@ export const api = {
   sendWorkerMessage: (taskId: string, intentId: string, message: string, requestId: string) =>
     post<{
       id: number;
-      state: "open" | "running" | "paused";
+      state: "running";
       accepted: true;
-      activity_seq: number;
       request_id: string;
     }>(`/tasks/${taskId}/intents/${intentId}/messages`, { message, request_id: requestId }),
   taskLLMResolution: (id: string) => get<TaskLLMResolutions>(`/tasks/${id}/llm/resolution`),

web/src/lib/mock/handler.ts

@@ -465,23 +465,23 @@ function sendMockWorkerMessage(
   }
   const intent = mockIntents.find((item) => item.id === id);
   if (!intent) return { ok: false, error: "意图不存在" };
-  if (intent.inherited || (intent.state !== "running" && intent.state !== "paused")) {
-    return { ok: false, state: intent.state, error: "Worker 状态已变化" };
+  if (intent.inherited || intent.state !== "paused") {
+    return { ok: false, state: intent.state, error: "仅已暂停的 Worker 可以发送消息，请先暂停" };
   }
   if (!normalizedMessage) return { ok: false, state: intent.state, error: "消息不能为空" };
   if (Array.from(normalizedMessage).length > 4000) {
     return { ok: false, state: intent.state, error: "消息不能超过 4000 个字符" };
   }
 
-  // The real endpoint stops the active turn, persists a normal user message,
-  // and immediately reopens the same intent. Keep the mock's transition in sync,
-  // then emulate a Worker reclaiming it shortly afterward.
-  intent.state = "open";
+  // The real endpoint transitions the intent paused->running, records the user turn,
+  // and runs it in a dedicated goroutine outside the worker pool. Keep the mock in
+  // sync: flip to running immediately and emit the visible user activity.
+  intent.state = "running";
   const activitySeq = nextMockWorkerMessageActivitySeq++;
   const workerMessage: MockWorkerMessage = {
     intentId: id,
     message: normalizedMessage,
-    state: "open",
+    state: "running",
     activitySeq,
   };
   mockWorkerMessages.set(normalizedRequestId, workerMessage);
@@ -494,12 +494,6 @@ function sendMockWorkerMessage(
     summary: normalizedMessage,
     detail: normalizedMessage,
   } satisfies Activity);
-  setTimeout(() => {
-    if (intent.state === "open") {
-      intent.state = "running";
-      workerMessage.state = "running";
-    }
-  }, 250);
   return {
     ok: true,
     state: workerMessage.state,
@@ -1008,9 +1002,8 @@ function route(m: string, path: string, seg: string[], q: URLSearchParams, b: Re
     if (!result.ok) throw new Error(result.error ?? "Worker 状态已变化");
     return {
       id: Number(id.replace(/\D/g, "")) || 0,
-      state: result.state ?? "open",
+      state: result.state ?? "running",
       accepted: true,
-      activity_seq: result.activitySeq ?? 0,
       request_id: result.requestId ?? "",
     };
   }