feat: flow 第 1 部分（骨架、研究开始、第零轮）与第零轮检验

按任务书 12 实现 src/flow：从账本现算下一步的纯函数、主循环、恢复入口、派模型任务和跑正式运行两个共用动作、冻结配置、基线、第零轮三个研究者阶段和入口分配，走到第 1 轮时停下。materials 导出 finalEntries、加 researcherId 和 StudyRecord。

审阅采纳两条：研究编号本机已用过时冻结前报错；docker run 没启动时写完结果就停下，不在本进程里无限起新编号。

eval/ 新增第零轮检验：起研究命令行、回放假模型、检验用 Jev 客户端、六问质量评估、16-real-1 回放、杀进程与两份同时跑。tsc 与 depcruise 也检查 eval/，新增 eval 只经 index.ts 用正式代码的规则。

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/flow/steps/round-zero.ts

@@ -0,0 +1,44 @@
+import { finalEntries } from "../../materials/index.ts";
+import { assignEntries as assign } from "../../rules/index.ts";
+import type { Json } from "../../vocab/index.ts";
+import { runModelTask } from "../model-task.ts";
+import type { Next } from "../next-step.ts";
+import { halt, USER_STOPPED, type Study, type StudyEnding } from "../study.ts";
+
+// 第零轮（方法.md 4.2）：三个研究者阶段派任务，认领之后由程序分配入口。
+
+/**
+ * 派一个研究者阶段里要派的人，同时跑，各自一个会话（任务书 12 第 2.6 节）。第零轮的提交种类交上来之后没有要另算的东西。
+ * 有人没交上（没交或出错），等这次派发的会话全部结束后停下，不打断别人（第 2.4 节）。
+ * 某个会话抛出内部错误时，也等别人结束再把它抛出去。
+ */
+export async function dispatchStage(s: Study, next: Extract<Next, { do: "dispatch" }>): Promise<StudyEnding | null> {
+  const settled = await Promise.allSettled(
+    next.actors.map((actor) => runModelTask(s, { kind: next.kind, actor, stageId: next.stageId, object: null, known: () => null })),
+  );
+  const failure = settled.find((r) => r.status === "rejected");
+  if (failure !== undefined) throw failure.reason;
+  if (s.stop.aborted) return USER_STOPPED;
+  const results = settled.map((r) => (r as PromiseFulfilledResult<Awaited<ReturnType<typeof runModelTask>>>).value);
+  const missed = results.flatMap(({ call, ending }) =>
+    ending.status === "notSubmitted" || ending.status === "failed" ? [{ call, text: `${ending.status === "failed" ? "出错" : "没交"}：${ending.reason}` }] : [],
+  );
+  if (missed.length === 0) return null;
+  return halt(s.ledger, `阶段 ${next.stageId} 有人没交上，等这次派发的会话全部结束后停下：${missed.map((m) => `调用 ${m.call}，${m.text}`).join("；")}`, missed.map((m) => m.call));
+}
+
+/**
+ * 分配（方法.md 4.2"分配规则"）：每人最后一份认领和最终有效的入口交给 rules 的 assignEntries，写一条入口分配决定。
+ * assignEntries 不在规则登记表里，规则名就写它，版本 1；没有方法参数，也不用随机。
+ */
+export function assignEntries(s: Study): void {
+  const roster = s.ledger.records().find((r) => r.kind === "stageOpen" && r.content.stage === "claim" && r.content.round === 0);
+  const claim = roster!.content as { stageId: string; roster: string[] };
+  const researchers = claim.roster.map((id) => {
+    const last = s.ledger.latestSubmission({ stageId: claim.stageId, author: id, kind: "claim", target: null, item: null });
+    return { id, choices: (last!.content.content as { choices: string[] }).choices };
+  });
+  const entries = finalEntries(s.ledger).map((e) => ({ id: e.id, author: e.author }));
+  const input = { researchers, entries };
+  s.ledger.append("decision", { decision: "entries", round: 0, rule: "assignEntries", ruleVersion: 1, params: null, seed: null, input, output: assign(input) as unknown as Json });
+}